chore(off-policy): clear redundant distributed grad average

[Gaiejj]

Description

Remove redundant distributed average gradient in off-policy algorithms

Motivation and Context

Resolve issue #252

• I have raised an issue to propose this change (required for new features and bug fixes)

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds core functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist

Go over all the following points, and put an x in all the boxes that apply.
If you are unsure about any of these, don't hesitate to ask. We are here to help!

• I have read the CONTRIBUTION guide. (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly. (required for a bug fix or a new feature)
• I have updated the documentation accordingly.
• I have reformatted the code using make format. (required)
• I have checked the code using make lint. (required)
• I have ensured make test pass. (required)

[codecov-commenter]

Codecov Report

Merging #253 (df234a3) into main (1a99b20) will increase coverage by 0.03%.
The diff coverage is 71.43%.

❗ Current head df234a3 differs from pull request most recent head 8f9d415. Consider uploading reports for the commit 8f9d415 to get more accurate results

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@@            Coverage Diff             @@
##             main     #253      +/-   ##
==========================================
+ Coverage   96.98%   97.01%   +0.03%     
==========================================
  Files         138      138              
  Lines        6994     6989       -5     
==========================================
- Hits         6783     6780       -3     
+ Misses        211      209       -2     

Impacted Files	Coverage Δ
omnisafe/algorithms/off_policy/sac.py	100.00% <ø> (ø)
omnisafe/algorithms/off_policy/td3.py	100.00% <ø> (ø)
omnisafe/algorithms/algo_wrapper.py	94.79% <60.00%> (+0.11%)	⬆️
omnisafe/algorithms/off_policy/ddpg.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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