Fix crash when prehandle snapshot (#4140)

[ti-chi-bot]

This is an automated cherry-pick of #4140

What problem does this PR solve?

Issue Number: close #4072

Problem Summary: When apply snapshot, it will first get a schema snapshot for decoding. And in the schema snapshot we store a pointer to the column infos. So if the schema of the column infos changed, the pointer may be invalid and it will cause crash.

What is changed and how it works?

Copy the value of the column infos instead of storing a pointer when creating schema snapshot.

Check List

Tests

• Unit test
• Integration test (3 tiflash nodes with two tiflash replica, under heavy dml + ddl workload and with region-shuffle-scheduler, the cluster works normally)
• Manual test (add detailed scripts or steps below)
• No code

Release note

Avoid the potential of crash when apply snapshot under heavy ddl scenario

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JaySon-Huang
• flowbehappy

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[JaySon-Huang]

/merge

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@JaySon-Huang: /merge in this pull request requires 2 approval(s).

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/merge

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[lidezhu]

/merge

[ti-chi-bot]

@lidezhu: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: d8c17fc

[sre-bot]

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