executor: remove EnablePointGetCache session var

[YangKeao]

What problem does this PR solve?

Issue Number: close #55696

Problem Summary:

These codes are not modified for a very long time, and there is no option to enable this session var. Therefore, I think maybe it's safe to remove it 🤔.

What changed and how does it work?

Simply remove the codes related to EnablePointGetCache.

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.
    This PR doesn't change the existing logic. The existing tests about normal point get should cover it.

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

[YangKeao]

I found a similar PR #48962 🤦. @Defined2014 Why do you close it?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.7898%. Comparing base (3d42e34) to head (9eddc89).
Report is 599 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #55697        +/-   ##
================================================
+ Coverage   72.9203%   74.7898%   +1.8695%     
================================================
  Files          1581       1582         +1     
  Lines        442365     442632       +267     
================================================
+ Hits         322574     331044      +8470     
+ Misses        99982      91292      -8690     
- Partials      19809      20296       +487     

Flag	Coverage Δ
integration	48.9566% <ø> (?)
unit	71.8769% <ø> (-0.1265%)	⬇️

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

Components	Coverage Δ
dumpling	52.9567% <ø> (ø)
parser	∅ <ø> (∅)
br	52.1762% <ø> (+6.9140%)	⬆️

[Defined2014]

I found a similar PR #48962 🤦. @Defined2014 Why do you close it?

The session variable is removed by an accident. And we try to add back it before #51008 But this was rejected, I think it's good to remove it. If I remember correctly, this feature was designed for POC and was never mentioned in the documentation.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Defined2014, lance6716
Once this PR has been reviewed and has the lgtm label, please assign easonn7 for approval. For more information see the Code Review Process.

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Needs approval from an approver in each of these files:

• OWNERS [Defined2014,lance6716]
• pkg/sessionctx/variable/OWNERS

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-27 09:58:16.149650358 +0000 UTC m=+864291.284100488: ☑️ agreed by Defined2014.
• 2024-08-27 14:03:58.630706369 +0000 UTC m=+879033.765156489: ☑️ agreed by lance6716.

[wjhuang2016]

GetMemCache should be removed too,

[lance6716]

/assign @yudongusa

[ti-chi-bot]

@lance6716: GitHub didn't allow me to assign the following users: yudongusa.

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In response to this:

/assign @yudongusa

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[ti-chi-bot]

PR needs rebase.

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[ti-chi-bot]

@YangKeao: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-integration-e2e-test	9eddc89	link	true	/test pull-integration-e2e-test

Full PR test history. Your PR dashboard.

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