[ISSUE #7757] Use CompositeByteBuf to prevent memory copy.

[dao-jun]

Brief Description

Use CompositeByteBuf instead of DirectByteBuf to prevent memory copy.

How Did You Test This Change?

Existing tests could cover the case.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (0d516ba) 43.20% compared to head (038e832) 43.16%.
Report is 308 commits behind head on develop.

Files	Patch %	Lines
...che/rocketmq/remoting/netty/FileRegionEncoder.java	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #7694      +/-   ##
=============================================
- Coverage      43.20%   43.16%   -0.04%     
- Complexity      9028     9808     +780     
=============================================
  Files           1107     1165      +58     
  Lines          78269    84545    +6276     
  Branches       10202    10980     +778     
=============================================
+ Hits           33813    36493    +2680     
- Misses         40222    43506    +3284     
- Partials        4234     4546     +312     

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[RongtongJin]

It would be better to provide some performance comparison data.