cmd/coordinator: remove the blacklist of the shootout target

The previous blacklisting was because of golang/go#12668, since fixed.

Further, the tests are now sharded (golang/go#12623) and this test
name doesn't even exist, so this change is a no-op.

Change-Id: Id141923e904a5aec91e53ba6f1d44e6cdf137cd2
Reviewed-on: https://go-review.googlesource.com/14773
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed