[integ-tests] Fix usage of --use-default-iam-credentials flag

[demartinofra]

Description of changes

PR #4652 was breaking the usage of --use-default-iam-credentials because the custom_cli_credentials param was being passed as a kwarg to the pcluster command.

As part of the fix I made the custom_cli_credentials an explicit argument assuming that generics kwargs are being used to propagate custom args to the pcluster commands. In this case this is a known argument we want to handle as part of the framework, therefore making it explicit with a default.

Tests

• Locally executed tests with and without the --use-default-iam-credentials flag

References

• [3.x] Add Integration tests for Resource Prefix #4652

Checklist

• Make sure you are pointing to the right branch and add a label in the PR title (i.e. 2.x vs 3.x)
• Check all commits' messages are clear, describing what and why vs how.
• Make sure to have added unit tests or integration tests to cover the new/modified code.
• Check if documentation is impacted by this change.

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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 #4732 (91fdf3e) into develop (876211e) will increase coverage by 0.07%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #4732      +/-   ##
===========================================
+ Coverage    89.10%   89.17%   +0.07%     
===========================================
  Files          163      163              
  Lines        14369    14369              
===========================================
+ Hits         12803    12814      +11     
+ Misses        1566     1555      -11     

Impacted Files	Coverage Δ
cli/src/pcluster/templates/cdk_builder_utils.py	96.69% <ø> (+4.13%)	⬆️
cli/src/pcluster/config/cluster_config.py	95.71% <0.00%> (+0.07%)	⬆️

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[himani2411]

For my reference, approving as this changes dont affect our Dev Jenkins and will only be used for local testing.