async_cluster: optimisations

[utkarshgupta137]

Pull Request check-list

• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to CHANGES file?

Description of change

• return true from execute_pipeline if there are any errors
• use todo list to speedup retries
• store initialisation node in CommandsParser object
• add sync context manager for pipeline
• use if/else instead of try/except
• make command a function argument in _determine_nodes & _determine_slot
• add async cluster pipeline benchmark script

[codecov-commenter]

Codecov Report

Merging #2205 (e5cc0f1) into master (4a73d85) will decrease coverage by 0.00%.
The diff coverage is 81.15%.

@@            Coverage Diff             @@
##           master    #2205      +/-   ##
==========================================
- Coverage   92.03%   92.03%   -0.01%     
==========================================
  Files         108      108              
  Lines       27631    27634       +3     
==========================================
+ Hits        25430    25432       +2     
- Misses       2201     2202       +1     

Impacted Files	Coverage Δ
redis/asyncio/cluster.py	89.93% <79.66%> (-0.16%)	⬇️
redis/asyncio/parser.py	80.76% <90.00%> (+0.76%)	⬆️

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[dvora-h]

Thanks as always @utkarshgupta137!