Remove the superflous SocketBuffer from asyncio PythonParser

[kristjanvalur]

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Description of change

asyncio PyhonParser was using a SocketBuffer class to store incoming data. This is probably a carry-over from the
non-async version, but in asyncio, it is not needed. We can read directly from the _stream which is a StreamReader with
an internal buffer of 64KB.

This change removes redundant code and speeds up python parsing by relying on already-provided buffering and readline() functionality.

[kristjanvalur]

In addition, the socket_read_size is now more or less unused. it is used by HiredisParser as the batch size to move between the input stream and the hiredis parser. I'd like to remove it from the Parsers, use an arbitrary large value in the HiredisParser, and instead use it when instantiating the stream, using open_connection(limit=socket_read_size) or similar which will directly affect read buffering.

[codecov-commenter]

Codecov Report

Base: 92.03% // Head: 92.03% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (f4aee4c) compared to base (bea00b1).
Patch coverage: 84.37% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2418      +/-   ##
==========================================
- Coverage   92.03%   92.03%   -0.01%     
==========================================
  Files         110      110              
  Lines       28737    28677      -60     
==========================================
- Hits        26448    26392      -56     
+ Misses       2289     2285       -4     

Impacted Files	Coverage Δ
redis/asyncio/connection.py	86.38% <81.48%> (-0.75%)	⬇️
tests/test_asyncio/test_connection.py	98.57% <100.00%> (+0.02%)	⬆️
tests/test_cluster.py	96.96% <0.00%> (ø)
tests/test_asyncio/test_search.py	98.61% <0.00%> (+0.34%)	⬆️

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[kristjanvalur]

@dvora-h , is this something you'd consided including in the next release? It sort of forms the conclusion to a lot of my asyncio related simplifications in the library.

[dvora-h]

@kristjanvalur Thanks for this!
Can you please remove the timeseries tests changes from this PR?
Because: 1. It is not related here, we prefer to do such things in separate PR's
2. Following changes in the module, this is happening there now and there is no need for it... (we have already changed the test accordingly)

[kristjanvalur]

Sure, I can remove that. Please understand, I find myself often adding unrelated fixes to unittests when doing these pull requests, because the unittests are sometimes very flaky. Of course they're not part of the PR as such, but I do like my PRs to pass the CI pipeline regardless.

[kristjanvalur]

Regarding the socket_read_size, I'll make a separate PR for that once this one is merged, so that you can evaluate that change separately.

[dvora-h]

Thanks @kristjanvalur for all your hard work!