ddl: support drop table for label rule

[rleungx]

What problem does this PR solve?

Closes #26693. It can be reviewed after #26511 is merged.

What is changed and how it works?

Add a rule for a table, show it from PD API:

mysql> alter table t1 attributes="attr";

# curl http://127.0.0.1:2379/pd/api/v1/config/region-label/rules
[
  {
    "id": "schema/test/t1",
    "labels": [
      {
        "key": "attr",
        "value": "true"
      },
      {
        "key": "db",
        "value": "test"
      },
      {
        "key": "table",
        "value": "t1"
      }
    ],
    "rule_type": "key-range",
    "rule": {
      "start_key": "7480000000000000ff355f720000000000fa",
      "end_key": "7480000000000000ff365f720000000000fa"
    }
  }
]

After GC finish:

# curl http://127.0.0.1:2379/pd/api/v1/config/region-label/rules
[]

What's Changed:

1. add GC logic for label rules
2. add UpdateLabelRules to batch update/delete the rules

Check List

Tests

• Unit test

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Yisaer
• xhebox

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[rleungx]

/cc @xhebox @Yisaer

[rleungx]

/run-check_dev_2

[Yisaer]

Rest lgtm

[xhebox]

/cc @morgo @djshow832

[morgo]

LGTM

[xhebox]

/merge

[ti-chi-bot]

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

Commit hash: 8a8842d88538b6d49e51153e07814e9075d7ef5e

[xhebox]

/merge

[ti-chi-bot]

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

Commit hash: 25967c8

[ti-chi-bot]

@rleungx: Your PR was out of date, I have automatically updated it for you.

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/run-all-tests

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[rleungx]

/rebuild