api: return not found when region doesn't exist

[lhy1024]

What problem does this PR solve?

Issue Number: Close #8868

What is changed and how does it work?

Check List

Tests

• Unit test
  Before:
  
  After:
  

Release note

None.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.31%. Comparing base (95bfbe6) to head (ebf6176).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8869      +/-   ##
==========================================
+ Coverage   76.25%   76.31%   +0.05%     
==========================================
  Files         463      463              
  Lines       70458    70474      +16     
==========================================
+ Hits        53731    53785      +54     
+ Misses      13369    13342      -27     
+ Partials     3358     3347      -11     

Flag	Coverage Δ
unittests	76.31% <100.00%> (+0.05%)	⬆️

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

[lhy1024]

tidb, tikv, tiup do not call region/key or region/id

[JmPotato]

My concern here is that some of the downstream components may rely on this behavior to retry (when the result is empty), will this break the compatibility?

[lhy1024]

My concern here is that some of the downstream components may rely on this behavior to retry (when the result is empty), will this break the compatibility?

this api is not used by tidb, tikv, tiup, it is used by pd-ctl

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JmPotato, rleungx

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• OWNERS [JmPotato,rleungx]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-12-25 08:12:57.866145934 +0000 UTC m=+1635767.954948475: ☑️ agreed by rleungx.
• 2024-12-25 08:36:21.339129132 +0000 UTC m=+1637171.427931675: ☑️ agreed by JmPotato.

[lhy1024]

/test pull-integration-realcluster-test