ci: remove github workflows and actions

[SanketD92]

Issue #, if available:

Description of changes:

Checklist:

• [ ] Have you successfully deployed to an AWS account with your changes?
• [ ] Have you written new tests for your core changes, as applicable?
• [ ] Have you successfully tested with your changes locally?
• [ ] If new dependencies have been added, have they been pinned to specific versions?
• [ ] Is this change also required on the AWS Solution version?
• [ ] Have you updated openapi.yaml if you made updates to API definition (including add, delete or update parameter and request data schema)?
• [ ] If you had to run manual tests, have you considered automating those tests by adding them to end-to-end tests?
• [ ] If you are updating the changelog and vending out a new release, have you updated versionNumber and versionDate in .defaults.yml

AS review ticket id:

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