This fixes a regression that snuck in with #17108.
When running a single test with `go test` the
regex wouldn't be used anymore.
This restores the old behavior.
Release Notes:
- Fixed a regression when running Go tests. A recent change dropped the
regex used to match single test names when using `go test` in tasks to
run tests. That could lead to more or the wrong tests being run. This
restores the old behavior.
Thorsten Ball
bf64c0899f