Only create tarballs once per run-tests (#48321)
When our `run-tests` util is used we can safely only create one instance
of the package tarballs and re-use for the tests and then cleaning up at
the end.
Ports changes from testing new workflow
https://github.com/vercel/next.js/commit/0ceae76bf405e7268e7a7350720b7ce3ccc181ed
