planner: simplify plan cache for fast point get

[qw4990]

What problem does this PR solve?

Issue Number: ref #50618

Problem Summary: planner: simplify plan cache for fast point get

What changed and how does it work?

planner: simplify plan cache for fast point get

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.

None

[codecov]

Codecov Report

Attention: Patch coverage is 89.47368% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 74.5627%. Comparing base (96f9797) to head (a9c52fc).
Report is 2 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #53090        +/-   ##
================================================
+ Coverage   72.4322%   74.5627%   +2.1305%     
================================================
  Files          1490       1490                
  Lines        429001     429135       +134     
================================================
+ Hits         310735     319975      +9240     
+ Misses        99020      89293      -9727     
- Partials      19246      19867       +621     

Flag	Coverage Δ
integration	49.1239% <84.2105%> (?)
unit	71.2834% <84.2105%> (-0.0326%)	⬇️

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

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	50.3848% <ø> (+9.0428%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, hawkingrei

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Needs approval from an approver in each of these files:

• OWNERS [AilinKid,hawkingrei]
• pkg/planner/OWNERS [AilinKid,hawkingrei]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-08 00:50:08.352711656 +0000 UTC m=+1009562.109847229: ☑️ agreed by AilinKid.
• 2024-05-08 01:00:07.788282779 +0000 UTC m=+1010161.545418352: ☑️ agreed by hawkingrei.