chore: migrate unit test to use await fulfillment

[phantumcode]

Issue #

Description

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.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.41%. Comparing base (31a0a6a) to head (4bee708).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3703      +/-   ##
==========================================
+ Coverage   68.40%   68.41%   +0.01%     
==========================================
  Files        1089     1089              
  Lines       37651    37651              
==========================================
+ Hits        25755    25760       +5     
+ Misses      11896    11891       -5     

Flag	Coverage Δ
API_plugin_unit_test	68.97% <ø> (ø)
AWSPluginsCore	65.81% <ø> (ø)
Amplify	48.14% <ø> (ø)
Analytics_plugin_unit_test	84.52% <ø> (ø)
Auth_plugin_unit_test	79.32% <ø> (-0.01%)	⬇️
DataStore_plugin_unit_test	81.45% <ø> (+0.08%)	⬆️
Geo_plugin_unit_test	72.00% <ø> (ø)
Logging_plugin_unit_test	62.87% <ø> (ø)
Predictions_plugin_unit_test	37.32% <ø> (ø)
PushNotifications_plugin_unit_test	86.21% <ø> (ø)
Storage_plugin_unit_test	76.75% <ø> (ø)
unit_tests	68.41% <ø> (+0.01%)	⬆️

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