Update function_with_custom_code_deploy integration test case

[hawflau]

Issue #, if available:

Description of changes:

• Fix flaky integration test case due to potentially conflicting Deployment Config name.

Description of how you validated changes:

• Run the modified test case and validated it passed

Checklist:

• Add/update unit tests using:
  • Correct values
  • Bad/wrong values (None, empty, wrong type, length, etc.)
  • Intrinsic Functions
• Add/update integration tests
• make pr passes
• Update documentation
• Verify transformed template deploys and application functions as expected

Examples?

Please reach out in the comments, if you want to add an example. Examples will be
added to sam init through https://github.com/awslabs/aws-sam-cli-app-templates/

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