planner: fix the issue that UnionAll didn't handle the range bump case (#52542)

[ti-chi-bot]

This is an automated cherry-pick of #52542

What problem does this PR solve?

Issue Number: close #52472

Problem Summary:

The UnionAll should use types.AggFieldType to aggregate the fieldTypes. This function will handle the bump of range. For example, the aggregate of signed and unsigned long will give signed long long.

What changed and how does it work?

Use types.AggFieldType instead of types.MergeFieldType.

This PR also makes types.MergeFieldType private, as it's easy to make such mistakes.

Check List

Tests

• 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.

Fix the issue that the content of the result of `union all` may overflow the type.

[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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/test-infra repository.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign hi-rustin for approval. For more information see the Code Review Process.

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

Needs approval from an approver in each of these files:

• OWNERS

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

[ti-chi-bot]

@ti-chi-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/build	3781969	link	true	/test build
idc-jenkins-ci-tidb/check_dev	3781969	link	true	/test check-dev
idc-jenkins-ci-tidb/unit-test	3781969	link	true	/test unit-test
idc-jenkins-ci-tidb/check_dev_2	3781969	link	true	/test check-dev2

Full PR test history. Your PR dashboard.

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/test-infra repository. I understand the commands that are listed here.