store/copr: partly revert pr/35975, do it correctly this time (#55196)

[ti-chi-bot]

This is an automated cherry-pick of #55196

What problem does this PR solve?

Issue Number: close #54969

Problem Summary:

What changed and how does it work?

#55155 try to revert pr/35975 but not clean, coupling with #41500 and bring bugs. PartitionNum is 1 even on non-partitioned table.

Do it correctly in this PR.
The new behaviour now:

• The 'select ... where ... order by ...' query will not reduce distsql concurrency to 2 (change)
• The simple 'select ... limit N' query, when N < 10000 , distsql concurrency is set to 1 (keep the behavior no change)
  • The same 'select ... limit N' query, on partitioned table, distsql concurrency is set to partition number (keep the behavior no change)

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

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-7.5@fa40bca). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #55211   +/-   ##
================================================
  Coverage               ?   72.2517%           
================================================
  Files                  ?       1413           
  Lines                  ?     412797           
  Branches               ?          0           
================================================
  Hits                   ?     298253           
  Misses                 ?      94795           
  Partials               ?      19749           

Flag	Coverage Δ
unit	72.2517% <100.0000%> (?)

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

Components	Coverage Δ
dumpling	52.9400% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.5535% <0.0000%> (?)

[windtalker]

lgtm

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Defined2014, windtalker

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-23 03:43:50.303399526 +0000 UTC m=+1451100.043823464: ☑️ agreed by Defined2014.
• 2024-09-23 04:00:01.378911011 +0000 UTC m=+1452071.119334973: ☑️ agreed by windtalker.