feat(router): allow the follower to handle QueryRegion

[JmPotato]

What problem does this PR solve?

Issue Number: ref #8690.

What is changed and how does it work?

Implement Follower Handle functionality for QueryRegion.

Check List

Tests

• Unit test
• Integration test

Release note

None.

[codecov]

Codecov Report

Attention: Patch coverage is 76.87075% with 34 lines in your changes missing coverage. Please review.

Project coverage is 75.89%. Comparing base (361a30d) to head (11dc2a0).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9196      +/-   ##
==========================================
+ Coverage   75.83%   75.89%   +0.06%     
==========================================
  Files         477      477              
  Lines       73439    73532      +93     
==========================================
+ Hits        55689    55810     +121     
+ Misses      14279    14261      -18     
+ Partials     3471     3461      -10     

Flag	Coverage Δ
unittests	75.89% <76.87%> (+0.06%)	⬆️

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[okJiang]

rest lgtm

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [rleungx]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-04-15 04:12:00.746384279 +0000 UTC m=+2748014.430620368: ☑️ agreed by rleungx.
• 2025-04-15 07:32:07.177919035 +0000 UTC m=+2760020.862155131: ☑️ agreed by okJiang.