expression: set `expr.RetType` as Expr.FieldType when pushdown to TiKV

[Defined2014]

What problem does this PR solve?

Issue Number: close #55677

Problem Summary:

What changed and how does it work?

Check List

Tests

• [ ] Unit test
• [x] Integration test
• [ ] Manual test (add detailed scripts or steps below)
• [ ] No need to test

  • [ ] I checked and no code files have been changed.

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[tiprow[bot]]

Hi @Defined2014. Thanks for your PR.

PRs from untrusted users cannot be marked as trusted with /ok-to-test in this repo meaning untrusted PR authors can never trigger tests themselves. Collaborators can still trigger tests on the PR using /test all.

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 88.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 56.4776%. Comparing base (2d1ed88) to head (78b313d). Report is 1032 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #55724         +/-   ##
=================================================
- Coverage   72.8465%   56.4776%   -16.3689%     
=================================================
  Files          1604       1730        +126     
  Lines        445737     629461     +183724     
=================================================
+ Hits         324704     355505      +30801     
- Misses       101006     250035     +149029     
- Partials      20027      23921       +3894     

Flag	Coverage Δ
integration	37.2391% <76.0000%> (?)
unit	72.0529% <84.0000%> (+0.0970%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.9567% <ø> (ø)
parser	∅ <ø> (∅)
br	52.8235% <ø> (+7.0860%)	:arrow_up:

[Defined2014]

/retest

[tiprow[bot]]

@Defined2014: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

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[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-09-10 05:57:35.575976134 +0000 UTC m=+335925.316400072: :ballot_box_with_check: agreed by tiancaiamao.
• 2024-09-10 06:06:19.154887139 +0000 UTC m=+336448.895311079: :ballot_box_with_check: agreed by XuHuaiyu.

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, tiancaiamao, XuHuaiyu

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

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~OWNERS~~ [AilinKid,XuHuaiyu,tiancaiamao]
• ~~pkg/expression/OWNERS~~ [XuHuaiyu]
• ~~pkg/planner/OWNERS~~ [AilinKid]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment

[Defined2014]

/retest

[tiprow[bot]]

@Defined2014: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

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 kubernetes-sigs/prow repository.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #56088.

[ti-chi-bot]

In response to a cherrypick label: new pull request could not be created: failed to create pull request against pingcap/tidb#release-7.5 from head ti-chi-bot:cherry-pick-55724-to-release-7.5: status code 422 not one of [201], body: {"message":"Validation Failed","errors":[{"resource":"PullRequest","code":"custom","message":"A pull request already exists for ti-chi-bot:cherry-pick-55724-to-release-7.5."}],"documentation_url":"https://docs.github.com/rest/pulls/pulls#create-a-pull-request","status":"422"}

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #56912.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #58154.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #59287. But this PR has conflicts, please resolve them!