Re-plan UNION plans to get type information

[frouioui]

Description

Related Issue(s)

• Performance regression: UNION in v19 #15466

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

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Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[codecov]

Codecov Report

Attention: Patch coverage is 19.80198% with 81 lines in your changes are missing coverage. Please review.

Project coverage is 65.61%. Comparing base (f889134) to head (00b25d8).
Report is 200 commits behind head on main.

Files	Patch %	Lines
go/vt/vtgate/planbuilder/operators/record.go	0.00%	27 Missing ⚠️
go/vt/vtgate/engine/record.go	0.00%	26 Missing ⚠️
go/vt/vtgate/engine/replan.go	0.00%	26 Missing ⚠️
go/vt/vtgate/planbuilder/operators/phases.go	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15476      +/-   ##
==========================================
- Coverage   65.65%   65.61%   -0.04%     
==========================================
  Files        1563     1566       +3     
  Lines      194395   194501     +106     
==========================================
+ Hits       127627   127630       +3     
- Misses      66768    66871     +103     

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[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.

[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.