ttl: always enable all read engines for TTL sessions

[YangKeao]

What problem does this PR solve?

Issue Number: close #56402

Problem Summary:

If a TiDB node doesn't enable TiKV read engine, running TTL task may fail if the table doesn't have tiflash replica.

What changed and how does it work?

This PR always enables all read engines for TTL sessions.

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

Fix the issue that if the `isolation-read.engines` config is set without `tikv`, the TTL task may fail.

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 12 lines in your changes missing coverage. Please review.

Project coverage is 57.8568%. Comparing base (f0b3bf0) to head (ee47ef7).
Report is 70 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #56604         +/-   ##
=================================================
- Coverage   73.3452%   57.8568%   -15.4884%     
=================================================
  Files          1628       1759        +131     
  Lines        449555     645830     +196275     
=================================================
+ Hits         329727     373657      +43930     
- Misses        99598     248372     +148774     
- Partials      20230      23801       +3571     

Flag	Coverage Δ
integration	38.2879% <17.8571%> (?)
unit	74.1597% <57.1428%> (+1.7061%)	⬆️

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

Components	Coverage Δ
dumpling	52.9478% <ø> (ø)
parser	∅ <ø> (∅)
br	53.1370% <ø> (+7.5292%)	⬆️

[YangKeao]

/retest

[bb7133]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bb7133, lcwangchao

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 [bb7133,lcwangchao]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-10-12 06:32:13.602615265 +0000 UTC m=+79930.751525081: ☑️ agreed by lcwangchao.
• 2024-10-22 02:50:04.825984322 +0000 UTC m=+319405.522774929: ☑️ agreed by bb7133.

[YangKeao]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #56805.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #56806.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #56807.