This would previously fail since arm64 binaries need to be downloaded.

To quote 'go help test':

The idiomatic way to disable test caching explicitly is to use -count=1

- Otherwise this fails on some of the omnibus builder images

https://gitlab.com/gitlab-org/gitlab-shell/-/merge_requests/718 will
make Go 1.19 the default for gitlab-shell. Per
https://github.com/golang/go/issues/51940, the dev.boringcrypto branch
no longer exists, and to support FIPS we need to pass along
`GOEXPERIMENT=boringcrypto`.

To do this, we just see if this `GOEXPERIMENT` is available with `go
version` rather than do some more complicated version-specific
comparison.