branch-4.0: [fix](cloud) Skip wait for async rowset warmup

[bobhan1]

Proposed changes

pick #62764
Backport upstream commit 24cb2f77cb248e0fd6c5329136c4a0fce3c52bd4 to branch-4.0.

This changes CloudWarmUpManager::warm_up_rowset so non-positive sync_wait_timeout_ms submits async rowset warmup work and returns immediately, while copying the rowset meta for the background task. Positive timeout waits now use an explicit finished flag to avoid returning on spurious wakeups.

The new unit test was adapted for the 4.0 include layout.

Root cause

Async rowset warmup still waited on a condition variable even when sync_wait_timeout_ms was non-positive.

Testing

git diff HEAD^ --check
./run-be-ut.sh --run --filter=CloudWarmUpManagerTest.* -j100

[hello-stephen]

Thank you for your contribution to Apache Doris.
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Please clearly describe your PR:

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?

[bobhan1]

run buildall

[hello-stephen]

BE UT Coverage Report

Increment line coverage 89.29% (25/28) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	53.25% (19418/36467)
Line Coverage	36.37% (181336/498536)
Region Coverage	32.97% (140825/427183)
Branch Coverage	33.85% (60958/180096)

[hello-stephen]

BE Regression && UT Coverage Report

Increment line coverage 89.29% (25/28) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	71.50% (25524/35700)
Line Coverage	54.37% (270556/497654)
Region Coverage	51.78% (223437/431503)
Branch Coverage	53.28% (96291/180729)