tso/local: remove dc location and local_locator.go

[okJiang]

What problem does this PR solve?

Issue Number: Ref #8802

What is changed and how does it work?

Check List

Tests

• Unit test
• Integration test

Release note

None.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov]

Codecov Report

Attention: Patch coverage is 80.24691% with 16 lines in your changes missing coverage. Please review.

Project coverage is 76.18%. Comparing base (f91605a) to head (73f0b6c).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8851      +/-   ##
==========================================
+ Coverage   75.82%   76.18%   +0.36%     
==========================================
  Files         460      458       -2     
  Lines       70637    70167     -470     
==========================================
- Hits        53557    53455     -102     
+ Misses      13702    13359     -343     
+ Partials     3378     3353      -25     

Flag	Coverage Δ
unittests	76.18% <80.24%> (+0.36%)	⬆️

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