cherry-pick #2229 to release-5.1
You can switch your code base to this Pull Request by using git-extras:

# In tics repo:
git pr https://github.com/pingcap/tics/pull/2240

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tics.git pr/2240:release-5.1-8f8b729e5c95

What problem does this PR solve?

Issue Number: related to #2199

Problem Summary: Suspicious that some tasks hold snapshot for a long time, prevent PageStorage from GCing old PageFiles

What is changed and how it works?

Add create_time and thread_id when creating snapshots. After PageStorage::gc, log the oldest snapshot living time and its thread_id.
We can trace to thread_id to know whether the snapshot is created for reading / background task.
When the create_time and thread_id and the period of logging files, we can know exactly which task holds the snapshot for a long time.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch:
• Related TiDB PR: infoschema: Add new columns for information_schema.tiflash_tables tidb#25678

Check List

Tests

• Manual test (add detailed scripts or steps below)
  • Deploy a TiFlash with these changes to check the logging

Side effects

• Performance regression
  • Consumes more CPU
  • Consumes more MEM

Release note

• No release note