[WIP] Ingest big snapshots by split

[breezewish]

What problem does this PR solve?

Issue Number: ref #5237

Problem Summary:

What is changed and how it works?

This PR changes the snapshot ingestion way. Previously we ingest snapshot into the delta layer. Now we ingest snapshot by replacing the entire segment.

This PR is a collection of everything. I will split it out to multiple small PRs.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

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[ti-chi-bot]

@breezewish: PR needs rebase.

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[breezewish]

Separated into smaller PRs. Closing.