fix: removed unsupported portfinder

[ammarkarachi]

Description of changes

Removed unsupported portfinder and replaced by get-port. Webpack-dev-server still hasn't

Issue #, if available

Description of how you validated changes

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies

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

[codecov-commenter]

Codecov Report

Merging #10269 (95ba1bd) into master (eff77da) will not change coverage.
The diff coverage is 66.66%.

@@           Coverage Diff           @@
##           master   #10269   +/-   ##
=======================================
  Coverage   54.28%   54.28%           
=======================================
  Files         850      850           
  Lines       46956    46956           
  Branches    10005    10005           
=======================================
  Hits        25490    25490           
  Misses      19448    19448           
  Partials     2018     2018           

Impacted Files	Coverage Δ
...ages/amplify-appsync-simulator/src/server/index.ts	93.93% <66.66%> (ø)
...plify-appsync-simulator/src/server/subscription.ts	39.83% <66.66%> (ø)

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[johnpc]

waiting for webpack-dev-server but otherwise lgtm

[sachscode]

LGTM

[ammarkarachi]

I will merge this and create another PR for Webpack