chore: Target code coverage to only library modules

[palpatim]

Previous configuration reported code coverage for the Test modules as well as
the library modules themselves. This change removes test targets from the
report.

Issue #, if available:

Description of changes:

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

[codecov]

Codecov Report

Merging #871 into main will decrease coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #871      +/-   ##
==========================================
- Coverage   64.25%   64.11%   -0.14%     
==========================================
  Files         770      852      +82     
  Lines       30421    33079    +2658     
==========================================
+ Hits        19546    21209    +1663     
- Misses      10875    11870     +995     

Flag	Coverage Δ
API_plugin_unit_test	62.49% <ø> (?)
Analytics_plugin_unit_test	72.38% <ø> (ø)
Auth_plugin_unit_test	15.79% <ø> (ø)
DataStore_plugin_unit_test	83.06% <ø> (ø)
Predictions_plugin_unit_test	42.11% <ø> (ø)
Storage_plugin_unit_test	74.74% <ø> (ø)
build_test_amplify	63.19% <ø> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ests/Sync/InitialSync/ReadyEventEmitterTests.swift	100.00% <ø> (ø)
...s/AWSHubPlugin/Internal/HubChannelDispatcher.swift	94.11% <0.00%> (-2.95%)	⬇️
...SAPICategoryPlugin/AWSAPIPlugin+RESTBehavior.swift	33.89% <0.00%> (ø)
...APICategoryPlugin/Operation/AWSRESTOperation.swift	59.74% <0.00%> (ø)
...goryPluginTests/AWSAPICategoryPluginTestBase.swift	93.93% <0.00%> (ø)
.../Support/Utils/RESTOperationRequest+Validate.swift	100.00% <0.00%> (ø)
...AWSAPICategoryPlugin+URLSessionDelegateTests.swift	100.00% <0.00%> (ø)
...upport/Utils/XCTestExpectation+ShouldTrigger.swift	50.00% <0.00%> (ø)
...equestInterceptor/UserPoolRequestInterceptor.swift	11.11% <0.00%> (ø)
...upport/Utils/RESTRequestUtils+ValidatorTests.swift	100.00% <0.00%> (ø)
... and 75 more

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[ruiguoamz]

Looks good