Remove redundant test_isa_mapping test (fixes #10077)

[daniel7an]

Summary

Removes the redundant test_isa_mapping test in t/unit/utils/test_collections.py.

Problem

As noted in #10077, the test_isa_mapping test checks that ConfigurationView is a subclass of Mapping, but this is already implied by the adjacent test_isa_mutable_mapping test which checks for MutableMapping. Since MutableMapping is a subclass of Mapping, the Mapping check is always True and fully redundant.

The inheritance chain: ConfigurationView -> ChainMap -> MutableMapping -> Mapping

Changes

• Removed test_isa_mapping from test_ConfigurationView (4 lines)
• Kept test_isa_mutable_mapping which provides the stronger guarantee

Testing

All 51 tests in t/unit/utils/test_collections.py pass.

[Copilot]

Pull request overview

This PR removes a redundant unit test in the collections utilities test suite, aligning the tests with the Python ABC inheritance hierarchy and reducing unnecessary assertions.

Changes:

• Removed test_isa_mapping from test_ConfigurationView because MutableMapping already implies Mapping.
• Kept test_isa_mutable_mapping as the stronger (and sufficient) inheritance assertion.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.52%. Comparing base (1690dd3) to head (44ad800).
⚠️ Report is 29 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10103   +/-   ##
=======================================
  Coverage   87.52%   87.52%           
=======================================
  Files         153      153           
  Lines       19382    19382           
  Branches     2229     2229           
=======================================
  Hits        16965    16965           
  Misses       2121     2121           
  Partials      296      296           

Flag	Coverage Δ
unittests	87.51% <ø> (ø)

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