tablecodec: fix write wrong prefix index value when collation is ascii_bin/latin1_bin (#24578)

[ti-srebot]

cherry-pick #24578 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/24680

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

git push [email protected]:ti-srebot/tidb.git pr/24680:release-5.0-ae36fbdb316f

---

What problem does this PR solve?

Issue Number:

close #24569
info #24548 (only address #24548 (comment), mainly issue seems have some other problem in tikv side)

Problem Summary:

prefix index will truncate value during insert, but for not utf8 collation, the code is wrong, it change type from string to bytes when handing truncate value to prefix len, at last, encode key will treat it as bytes and miss handling collation's trim space logic.

this issue need:

• prefix column index
• end with space after trimmed to the prefix length

the question maybe meet:

• unique index's duplicate check doesn't work for clustered or nonclustered index table
• admin check table should be fail when table is clustered index table

What is changed and how it works?

What's Changed, How it Works:

set it as string type if before truncating it's string type.

Related changes

• Need to cherry-pick to the release branch 5.0

Check List

Tests

• Unit test

Side effects

• n/a

Release note

• Fix write wrong prefix index value when collation is ascii_bin/latin1_bin

[ti-srebot]

/run-all-tests

[ti-srebot]

@lysu you're already a collaborator in bot's repo.

[cfzjywxk]

/lgtm

[wjhuang2016]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• cfzjywxk
• wjhuang2016

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by writing /lgtm in a comment.
Reviewer can cancel approval by writing /lgtm cancel in a comment.

[lysu]

@sticnarf CI seems back to green, please help merge again if free ~ :)

[ti-chi-bot]

@sticnarf: Thanks for your review. The bot only counts /lgtm from reviewers and higher roles in list, but you're still welcome to leave your comments.

In response to this:

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[sticnarf]

@sticnarf CI seems back to green, please help merge again if free ~ :)

To my understanding, only the release manager can merge the PRs into release branches.

[cfzjywxk]

/merge

[ti-chi-bot]

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

Commit hash: e15f879