robustness: implement cluster client endpoint switching

[henrybear327]

Introduce optional cluster client endpoint switching.

This would allow us to test out the client reconnection behaviors, such as the resumable guarantee for watches.

Used in #21472

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.92%. Comparing base (b397b7d) to head (9894653).

⚠️ Current head 9894653 differs from pull request most recent head 2080344

Please upload reports for the commit 2080344 to get more accurate results.

Additional details and impacted files

see 34 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #21471      +/-   ##
==========================================
- Coverage   68.40%   67.92%   -0.49%     
==========================================
  Files         428      428              
  Lines       35291    35291              
==========================================
- Hits        24142    23972     -170     
- Misses       9748     9910     +162     
- Partials     1401     1409       +8     

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[henrybear327]

/retest