Close validation progress bar before updating training bar

[awaelchli]

What does this PR do?

This fixes a minor visual glitch with the TQDM progress bar observed in the PyCharm terminal.

Before:

Validation:   0%|          | 0/4 [00:00<?, ?it/s]
Validation DataLoader 0:   0%|          | 0/4 [00:00<?, ?it/s]
Validation DataLoader 0:  50%|█████     | 2/4 [00:00<00:00,  3.94it/s]
Epoch 1: 100%|██████████| 8/8 [00:03<00:00,  2.63it/s, v_num=67]

(The validation bar is left incomplete before switching to training)

Now:

Validation DataLoader 0:   0%|          | 0/4 [00:00<?, ?it/s]
Validation DataLoader 0:  50%|█████     | 2/4 [00:00<00:00,  3.97it/s]
Validation DataLoader 0: 100%|██████████| 4/4 [00:01<00:00,  3.96it/s]
Epoch 1: 100%|██████████| 8/8 [00:03<00:00,  2.63it/s, v_num=66]

(The validation bar is complete)

Before submitting

• Was this discussed/agreed via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you list all the breaking changes introduced by this pull request?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or minor internal changes/refactors)

PR review

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Reviewer checklist

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cc @Borda @awaelchli

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-11, lightning, 3.8, 1.11)	success	✅
pl-cpu (macOS-11, lightning, 3.9, 1.12)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 1.13)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 2.0)	success	✅
pl-cpu (macOS-11, lightning, 3.8, 1.11, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 1.11)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.9, 1.12)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 1.13)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.0)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 1.11, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 1.11)	success	✅
pl-cpu (windows-2022, lightning, 3.9, 1.12)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 1.13)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.0)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 1.11, oldest)	success	✅
pl-cpu (macOS-11, pytorch, 3.8, 1.13)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.8, 1.13)	success	✅
pl-cpu (windows-2022, pytorch, 3.8, 1.13)	success	✅
pl-cpu (macOS-12, pytorch, 3.11, 2.0)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.11, 2.0)	success	✅
pl-cpu (windows-2022, pytorch, 3.11, 2.0)	success	✅

These checks are required after the changes to src/lightning/pytorch/callbacks/progress/tqdm_progress.py.

🟢 pytorch_lightning: Azure GPU

Check ID	Status
[pytorch-lightning (GPUs) (testing Lightning	latest)](https://dev.azure.com/Lightning-AI/72ab7ed8-b00f-4b6e-b131-3388f7ffafa7/_build/results?buildId=173613&view=logs&jobId=47e66f3c-897a-5428-da11-bf5c7745762e)	success
[pytorch-lightning (GPUs) (testing PyTorch	latest)](https://dev.azure.com/Lightning-AI/72ab7ed8-b00f-4b6e-b131-3388f7ffafa7/_build/results?buildId=173613&view=logs&jobId=3f274fac-2e11-54ca-487e-194c91f3ae9f)	success

These checks are required after the changes to src/lightning/pytorch/callbacks/progress/tqdm_progress.py.

🟢 pytorch_lightning: Benchmarks

Check ID	Status
lightning.Benchmarks	success	✅

These checks are required after the changes to src/lightning/pytorch/callbacks/progress/tqdm_progress.py.

🟢 pytorch_lightning: Docs

Check ID	Status
docs-make (pytorch, doctest)	success	✅
docs-make (pytorch, html)	success	✅

These checks are required after the changes to src/lightning/pytorch/callbacks/progress/tqdm_progress.py.

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to src/lightning/pytorch/callbacks/progress/tqdm_progress.py.

🟢 install

Check ID	Status
install-pkg (ubuntu-22.04, app, 3.8)	success	✅
install-pkg (ubuntu-22.04, app, 3.11)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.8)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.11)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.8)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.11)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.8)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.11)	success	✅
install-pkg (ubuntu-22.04, notset, 3.8)	success	✅
install-pkg (ubuntu-22.04, notset, 3.11)	success	✅
install-pkg (macOS-12, app, 3.8)	success	✅
install-pkg (macOS-12, app, 3.11)	success	✅
install-pkg (macOS-12, fabric, 3.8)	success	✅
install-pkg (macOS-12, fabric, 3.11)	success	✅
install-pkg (macOS-12, pytorch, 3.8)	success	✅
install-pkg (macOS-12, pytorch, 3.11)	success	✅
install-pkg (macOS-12, lightning, 3.8)	success	✅
install-pkg (macOS-12, lightning, 3.11)	success	✅
install-pkg (macOS-12, notset, 3.8)	success	✅
install-pkg (macOS-12, notset, 3.11)	success	✅
install-pkg (windows-2022, app, 3.8)	success	✅
install-pkg (windows-2022, app, 3.11)	success	✅
install-pkg (windows-2022, fabric, 3.8)	success	✅
install-pkg (windows-2022, fabric, 3.11)	success	✅
install-pkg (windows-2022, pytorch, 3.8)	success	✅
install-pkg (windows-2022, pytorch, 3.11)	success	✅
install-pkg (windows-2022, lightning, 3.8)	success	✅
install-pkg (windows-2022, lightning, 3.11)	success	✅
install-pkg (windows-2022, notset, 3.8)	success	✅
install-pkg (windows-2022, notset, 3.11)	success	✅

These checks are required after the changes to src/lightning/pytorch/callbacks/progress/tqdm_progress.py.

---

Thank you for your contribution! 💜

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[codecov]

Codecov Report

Merging #18503 (6e561c5) into master (4512265) will decrease coverage by 34%.
The diff coverage is 100%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #18503      +/-   ##
==========================================
- Coverage      84%      50%     -34%     
==========================================
  Files         427      419       -8     
  Lines       33364    33218     -146     
==========================================
- Hits        28113    16683   -11430     
- Misses       5251    16535   +11284     

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