* backport all gha migration changes to release/1.13.x
* remove the .circleci directory
* remove references to circleci configuration from pre-commit hook
* remove reference to .circleci in Makefile
* port change to how gofumpt is executed in Makefile
* add gotestsum to tools/tools.go
* remove postgresql/scram package from generate-test-package-lists.sh since it didn't exist in release 1.13 or earlier
* blank out environment variables to allow test to properly function
* use go:embed to load files into test
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Co-authored-by: Kuba Wieczorek <kuba.wieczorek@hashicorp.com>
