Use file path as cache key (#1852)

[ti-srebot]

cherry-pick #1852 to release-4.0
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/1861

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

git push git@github.com:ti-srebot/tics.git pr/1861:release-4.0-7bb9a84fe7f2

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What problem does this PR solve?

Issue Number: close #1352

Problem Summary:

What is changed and how it works?

What's Changed:

Use file path as cache key instead of a 128 bits hash code.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch:

Check List

Tests

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

Side effects

Release note

[JaySon-Huang]

Mark those hash_salt unused or delete them at all as #1866 does. And resolve the conflicts.

[JinheLin]

/run-all-tests

[JaySon-Huang]

LGTM