build: use shared browserslist config

[Jawayria]

Removes custom browserslist configuration in favor of using a shared configuration.
Removes is-es5 check in CI since ES5 was only needed for IE 11 support which is dropped. The supported browsers defined by the shared configuration all natively support ES6.
This change reduces the resultant asset bundle size.

Created this PR due to some issues in rebasing the older PR.

For all changes

• Ensure adequate tests are in place (or reviewed existing tests cover changes)

Only if submitting a visual change

• Ensure to attach screenshots
• Ensure to have UX team confirm screenshots

[codecov]

Codecov Report

Merging #238 (27a7800) into main (c7d5eca) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #238   +/-   ##
=======================================
  Coverage   82.47%   82.47%           
=======================================
  Files          37       37           
  Lines         582      582           
  Branches      185      185           
=======================================
  Hits          480      480           
  Misses         99       99           
  Partials        3        3           

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[Jawayria]

Frontend Bom will be carrying these forward.
cc: @abdullahwaheed