[CELEBORN-1626] group mapTask

[zaynt4606]

What changes were proposed in this pull request?

Why are the changes needed?

Does this PR introduce any user-facing change?

How was this patch tested?

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 32.17%. Comparing base (165e914) to head (41fba8d).
Report is 24 commits behind head on main.

Files with missing lines	Patch %	Lines
...born/common/protocol/message/ControlMessages.scala	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2771      +/-   ##
==========================================
- Coverage   32.35%   32.17%   -0.17%     
==========================================
  Files         329      329              
  Lines       19511    19697     +186     
  Branches     1752     1774      +22     
==========================================
+ Hits         6311     6336      +25     
- Misses      12855    13015     +160     
- Partials      345      346       +1     

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