ci: fix stress test workflow

[5d]

Issue #

Description

There is an issue to use get_platform_parameters composite action in stress test workflow.

Related action workflows:

• https://github.com/aws-amplify/amplify-swift/actions/runs/7494183065/job/20401536288
• https://github.com/aws-amplify/amplify-swift/actions/runs/7507029707/job/20439736522

The problem was resolved by combining the get-platform-build-params and prepare-for-test jobs, and exporting the results from the get-platform-build-params job separately.

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-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3719cca) 67.88% compared to head (c58ca27) 68.06%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3469      +/-   ##
==========================================
+ Coverage   67.88%   68.06%   +0.17%     
==========================================
  Files        1079     1079              
  Lines       36356    36356              
==========================================
+ Hits        24681    24746      +65     
+ Misses      11675    11610      -65     

Flag	Coverage Δ
API_plugin_unit_test	67.07% <ø> (ø)
AWSPluginsCore	64.13% <ø> (ø)
Amplify	48.10% <ø> (ø)
Analytics_plugin_unit_test	81.16% <ø> (ø)
Auth_plugin_unit_test	78.98% <ø> (+0.06%)	⬆️
CoreMLPredictions_plugin_unit_test	59.44% <ø> (ø)
DataStore_plugin_unit_test	81.34% <ø> (+0.88%)	⬆️
Geo_plugin_unit_test	70.75% <ø> (ø)
Logging_plugin_unit_test	63.34% <ø> (ø)
Predictions_plugin_unit_test	37.16% <ø> (ø)
PushNotifications_plugin_unit_test	87.13% <ø> (ø)
Storage_plugin_unit_test	77.51% <ø> (-0.04%)	⬇️
unit_tests	68.06% <ø> (+0.17%)	⬆️

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[thisisabhash]

For future reference, can we update the description of the PR with more details of the issue and steps taken to solve it?