fix(pipelines): action name FileAsset changed when publishAssetsInParallel is false

[Tietew]

Issue # (if applicable)

Closes #34042.

Reason for this change

The action name in Assets stage has been changed from FileAssetN to the display name of the asset in #33844.

When pipeline's publishAssetsInParallel is false, the action name is also changed to the display name of the first asset in stages instead of FileAsset.
The action uploads all assets, therefore, its name should indicate "all assets" rather than the first asset.

Description of changes

Use id as node's display name when singlePublisher is true (pipeline's publishAssetsInParallel is false), instead of stackAsset.displayName.

Describe any new or updated permissions being added

N/A

Description of how you validated changes

Added a unit test and a integ test.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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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

All modified and coverable lines are covered by tests ✅

Project coverage is 83.98%. Comparing base (994e952) to head (92c7ee5).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #34049   +/-   ##
=======================================
  Coverage   83.98%   83.98%           
=======================================
  Files         120      120           
  Lines        6976     6976           
  Branches     1178     1178           
=======================================
  Hits         5859     5859           
  Misses       1005     1005           
  Partials      112      112           

Flag	Coverage Δ
suite.unit	83.98% <ø> (ø)

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

Components	Coverage Δ
packages/aws-cdk	∅ <ø> (∅)
packages/aws-cdk-lib/core	83.98% <ø> (ø)

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[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 92c7ee5
• Result: SUCCEEDED
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