chore: ensure docker file runs as non root user

[GavinZZ]

Reason for this change

Fix Code Scanner issue

By not specifying a USER, a program in the container may run as 'root'. This is a security hazard.
If an attacker can control a process running as root, they may have control over the container.   
Ensure that the last USER in a Dockerfile is a USER other than 'root'.

Description of changes

Create a new group and attach the user to the group. The dockerfile already gives necessary permissions with statements like chmod 777

Description of how you validated changes

N/A

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 81.48%. Comparing base (b049fa8) to head (61654f1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #32976   +/-   ##
=======================================
  Coverage   81.48%   81.48%           
=======================================
  Files         226      226           
  Lines       13768    13768           
  Branches     2416     2416           
=======================================
  Hits        11219    11219           
  Misses       2271     2271           
  Partials      278      278           

Flag	Coverage Δ
suite.unit	81.48% <ø> (ø)

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Components	Coverage Δ
packages/aws-cdk	80.89% <ø> (ø)
packages/aws-cdk-lib/core	82.10% <ø> (ø)

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AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 61654f1
• Result: SUCCEEDED
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