fix(ec2-alpha): addInternetGW handles shared route table for subnets

[shikha372]

Issue # (if applicable)

Closes #33672

Reason for this change

Description of changes

Describe any new or updated permissions being added

Description of how you validated changes

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 82.38%. Comparing base (2623e00) to head (344de8c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #33824   +/-   ##
=======================================
  Coverage   82.38%   82.38%           
=======================================
  Files         120      120           
  Lines        6937     6937           
  Branches     1170     1170           
=======================================
  Hits         5715     5715           
  Misses       1119     1119           
  Partials      103      103           

Flag	Coverage Δ
suite.unit	82.38% <ø> (ø)

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Components	Coverage Δ
packages/aws-cdk	∅ <ø> (∅)
packages/aws-cdk-lib/core	82.38% <ø> (ø)

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[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 344de8c
• Result: FAILED
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