fix(auth): clear credentials values only if namespacing has changed

[harsh62]

Description

Added a check to ONLY remove the credentials if both namespace and configuration has changed.

General Checklist

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• New or updated tests include Given When Then inline code documentation and are named accordingly testThing_condition_expectation()
• If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

API Breakage Report

✅ No Public API Breaking Change detected

[codecov]

Codecov Report

Attention: Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.

Project coverage is 68.52%. Comparing base (bdfa37a) to head (c44d4ea).
Report is 5 commits behind head on main.

Files	Patch %	Lines
...ions/Helpers/FetchAuthSessionOperationHelper.swift	94.11%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3827      +/-   ##
==========================================
- Coverage   68.62%   68.52%   -0.11%     
==========================================
  Files        1080     1080              
  Lines       37635    37603      -32     
==========================================
- Hits        25827    25767      -60     
- Misses      11808    11836      +28     

Flag	Coverage Δ
API_plugin_unit_test	68.96% <ø> (ø)
AWSPluginsCore	68.56% <ø> (ø)
Amplify	47.56% <ø> (ø)
Analytics_plugin_unit_test	84.52% <ø> (ø)
Auth_plugin_unit_test	80.00% <94.73%> (+0.34%)	⬆️
DataStore_plugin_unit_test	81.26% <ø> (-1.04%)	⬇️
Geo_plugin_unit_test	72.00% <ø> (ø)
Logging_plugin_unit_test	62.95% <ø> (ø)
Predictions_plugin_unit_test	36.86% <ø> (ø)
PushNotifications_plugin_unit_test	86.21% <ø> (ø)
Storage_plugin_unit_test	76.81% <ø> (ø)
unit_tests	68.52% <94.73%> (-0.11%)	⬇️

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[github-actions]

API Breakage Report

✅ No Public API Breaking Change detected