planner: add projections to keep join keys as `col=col` (#52989)

[ti-chi-bot]

This is an automated cherry-pick of #52989

What problem does this PR solve?

Issue Number: close #46556

Problem Summary: planner: add projections to keep join keys as col=col

What changed and how does it work?

In some cases, after creating new EQ function, the 2 args might not be column anymore, which breaks the assumption that join eq keys must be col=col, to handle this, inject 2 projections.

Check List

Tests

• [x] Unit test
• [ ] 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

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-05-16 06:16:21.132079428 +0000 UTC m=+1720334.889215000: :ballot_box_with_check: agreed by qw4990.
• 2024-05-16 06:20:49.856405523 +0000 UTC m=+1720603.613541139: :ballot_box_with_check: agreed by elsa0520.

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: elsa0520, hawkingrei, qw4990, winoros

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

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/pingcap/tidb/blob/release-8.1/OWNERS)~~ [elsa0520,hawkingrei,qw4990,winoros] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:exclamation: No coverage uploaded for pull request base (release-8.1@ff5eb17). Click here to learn what that means.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-8.1 #53326 +/- ## ================================================ Coverage ? 71.1706% ================================================ Files ? 1465 Lines ? 421390 Branches ? 0 ================================================ Hits ? 299906 Misses ? 101004 Partials ? 20480 ``` | [Flag](https://app.codecov.io/gh/pingcap/tidb/pull/53326/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | Coverage Δ | | |---|---|---| | [unit](https://app.codecov.io/gh/pingcap/tidb/pull/53326/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `71.1706% <100.0000%> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap#carryforward-flags-in-the-pull-request-comment) to find out more. | [Components](https://app.codecov.io/gh/pingcap/tidb/pull/53326/components?src=pr&el=components&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | Coverage Δ | | |---|---|---| | [dumpling](https://app.codecov.io/gh/pingcap/tidb/pull/53326/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `53.9957% <0.0000%> (?)` | | | [parser](https://app.codecov.io/gh/pingcap/tidb/pull/53326/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `∅ <0.0000%> (?)` | | | [br](https://app.codecov.io/gh/pingcap/tidb/pull/53326/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `40.9738% <0.0000%> (?)` | |