[fix](block) fix be core while mutable block merge may cause different row size between columns in origin block (#28850)

[caiconghui]

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...

[caiconghui]

run buildall

[github-actions]

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

[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 37.80% (8005/21175)
Line Coverage: 29.48% (65018/220556)
Region Coverage: 28.97% (33472/115543)
Branch Coverage: 24.85% (17182/69156)
Coverage Report: http://coverage.selectdb-in.cc/coverage/42f916c7e1b5a6c1b8e01c6a8f9a9d093271c8c2_42f916c7e1b5a6c1b8e01c6a8f9a9d093271c8c2/report/index.html

[doris-robot]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 48.82 seconds
stream load tsv: 564 seconds loaded 74807831229 Bytes, about 126 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: 29.8 seconds inserted 10000000 Rows, about 335K ops/s
storage size: 17168242388 Bytes

[HappenLee]

LGTM

[github-actions]

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

[github-actions]

PR approved by anyone and no changes requested.

[xiaokang]

#28850

[xiaokang]

#27943