Pick "[Bug](cooldown) Fix problem that followers may never completely coold…

[platoneko]

…own (#28561)"

Proposed changes

Issue Number: close #xxx

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[xiaokang]

run buildall

[dataroaring]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.

[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 37.85% (8016/21181)
Line Coverage: 29.53% (65169/220718)
Region Coverage: 28.96% (33485/115612)
Branch Coverage: 24.83% (17179/69198)
Coverage Report: http://coverage.selectdb-in.cc/coverage/4860d96943376cf7032e452fce208dd32d3c9cb0_4860d96943376cf7032e452fce208dd32d3c9cb0/report/index.html

[doris-robot]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 47.35 seconds
stream load tsv: 569 seconds loaded 74807831229 Bytes, about 125 MB/s
stream load json: 20 seconds loaded 2358488459 Bytes, about 112 MB/s
stream load orc: 65 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 32 seconds loaded 861443392 Bytes, about 25 MB/s
insert into select: 29.6 seconds inserted 10000000 Rows, about 337K ops/s
storage size: 17163383924 Bytes