[fix](regression) avoid physical row count wait in partition stats case

[shuke987]

Summary

• Remove the show index stats physical row count polling from partition_key_minmax.
• Rely on analyze table ... with sync and keep cached stats/explain assertions for the planner stats under test.

Testing

• git diff --check -- regression-test/suites/query_p0/stats/partition_key_minmax.groovy
• Not run: no confirmed regression test environment for this case.

[hello-stephen]

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1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
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4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[shuke987]

run buildall

[shuke987]

Superseded by #65180.