internal/testenv: TestHasGoBuild failures on the LUCI noopt builders [1.21 backport]

[gopherbot]

@mknyszek requested issue #65470 to be considered for backport to the next 1.21 minor release.

@gopherbot Please open backport issues. This issue should be fixed as it means the LUCI noopt builder consistently fails on release branches. The fix is test-only, so very safe.

[gopherbot]

Change https://go.dev/cl/560518 mentions this issue: [release-branch.go1.21] internal/testenv: allow "-noopt" anywhere in builder name in test

[gopherbot]

Closed by merging f997dfd to release-branch.go1.21.