Fix resource usage and cleanup Mocks in the unit tests

[kristjanvalur]

Pull Request check-list

Please make sure to review and check all of these items:

• Do tests and lints pass with this change?
• 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)?
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Description of change

In pr #2911, we uncovered some problems in the unittests.

• There were missing "await" calls in the tests for test_cwe_404.py. asyncio.wait() must not wait for coroutines directly (this will be banned in 3.11) but must use tasks.
• Some AsyncMocks didn't use spec arguments and so methods, which weren't async, caused resource warnings. Mocking should use spec when possible.
• Mocking done to Redis objects when simulating a cluster in nocluster mode was not done and so the test suite would attempt to return mock objects to a connection pool that had never issued them.

In addition, a fix to a permanently disabled Unix connection test is included.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03% 🎉

Comparison is base (1596ac6) 91.28% compared to head (78140b0) 91.31%.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2936      +/-   ##
==========================================
+ Coverage   91.28%   91.31%   +0.03%     
==========================================
  Files         126      126              
  Lines       32398    32406       +8     
==========================================
+ Hits        29573    29592      +19     
+ Misses       2825     2814      -11     

Files Changed	Coverage Δ
tests/conftest.py	86.08% <100.00%> (+0.05%)	⬆️
tests/test_asyncio/conftest.py	85.41% <100.00%> (+0.52%)	⬆️
tests/test_asyncio/test_cluster.py	96.93% <100.00%> (ø)
tests/test_asyncio/test_cwe_404.py	100.00% <100.00%> (ø)
tests/test_connect.py	96.99% <100.00%> (+9.77%)	⬆️

... and 4 files with indirect coverage changes

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