[v2] Modifies botocore tests to use the defaults created in configprovider.py

[aemous]

Issue #, if available:

• Modifies the tests to use the defaults created in configprovider.py boto/botocore#3334

Description of changes:

• Ports Modifies the tests to use the defaults created in configprovider.py boto/botocore#3334 into our vendored botocore
• Import get_botocore_default_config_mapping to our test utilities so botocore-specific test imports are preserved.
• Modify the test test_max_attempts_expected_if_retries_is_none in tests/unit/botocore/test_args.py to reflect the fact that CLI v2 uses a default max_attempts value of 3, which is not the case for botocore.
  • In particular, I changed the name of the test to test_max_attempts_expected_if_retries_is_none, and I changed the expected assertion to be that max_attempts is the expected default CLI v2 value (3).

Description of tests:

• Ran and passed all botocore unit tests

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (0cb6373) to head (81ef44d).
Report is 56 commits behind head on v2.

Additional details and impacted files

@@    Coverage Diff     @@
##   v2   #9209   +/-   ##
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