fix(cli-integ): proxy test is being throttled by ecr

[iliapolo]

We are seeing sporadic throttling errors:

 💻 docker run --net=bridge --rm -v /tmp:/tmp -v /home/runner:/home/runner -v /tmp/cdk-integ-0ffcgkzpab:/tmp/cdk-integ-0ffcgkzpab -e HOME -e AWS_ACCESS_KEY_ID -e AWS_SECRET_ACCESS_KEY -e AWS_SESSION_TOKEN -w /tmp/cdk-integ-0ffcgkzpab --cap-add=NET_ADMIN public.ecr.aws/ubuntu/ubuntu:24.04_stable /tmp/cdk-integ-0ffcgkzpab/script.sh
  Unable to find image 'public.ecr.aws/ubuntu/ubuntu:24.04_stable' locally
  24.04_stable: Pulling from ubuntu/ubuntu
  docker: toomanyrequests: Rate exceeded.
  See 'docker run --help'.
  'docker run --net=bridge --rm -v /tmp:/tmp -v /home/runner:/home/runner -v /tmp/cdk-integ-0ffcgkzpab:/tmp/cdk-integ-0ffcgkzpab -e HOME -e AWS_ACCESS_KEY_ID -e AWS_SECRET_ACCESS_KEY -e AWS_SESSION_TOKEN -w /tmp/cdk-integ-0ffcgkzpab --cap-add=NET_ADMIN public.ecr.aws/ubuntu/ubuntu:24.04_stable /tmp/cdk-integ-0ffcgkzpab/script.sh' exited with error code 125.Error: 'docker run --net=bridge --rm -v /tmp:/tmp -v /home/runner:/home/runner -v /tmp/cdk-integ-0ffcgkzpab:/tmp/cdk-integ-0ffcgkzpab -e HOME -e AWS_ACCESS_KEY_ID -e AWS_SECRET_ACCESS_KEY -e AWS_SESSION_TOKEN -w /tmp/cdk-integ-0ffcgkzpab --cap-add=NET_ADMIN public.ecr.aws/ubuntu/ubuntu:24.04_stable /tmp/cdk-integ-0ffcgkzpab/script.sh' exited with error code 125.
      at ChildProcess.<anonymous> (/home/runner/work/aws-cdk-cli/aws-cdk-cli/lib/shell.ts:109:22)
      at ChildProcess.emit (node:events:524:28)
      at maybeClose (node:internal/child_process:1104:16)
      at Process.ChildProcess._handle.onexit (node:internal/child_process:304:5)
  ::endgroup::

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