bug(cmd/gazelle): :gazelle_test is broken on Bzlmod

[tyler-french]

It references go_sdk by name, which is not the name of a repository registered.

We should register the sdk under this name, but we don't want to collide with users who also choose to use go_sdk naming convention.

ERROR: no such package '@@[unknown repo 'go_sdk' requested from @@]//': The repository '@@[unknown repo 'go_sdk' requested from @@]' could not be resolved: No repository visible as '@go_sdk' from main repository
ERROR: /home/user/bazel-gazelle/cmd/gazelle/BUILD.bazel:43:8: no such package '@@[unknown repo 'go_sdk' requested from @@]//': The repository '@@[unknown repo 'go_sdk' requested from @@]' could not be resolved: No repository visible as '@go_sdk' from main repository and referenced by '//cmd/gazelle:gazelle_test'
Use --verbose_failures to see the command lines of failed build steps.

[alimoli]

Same here, just on building. I am trying to migrate from WORKSPACE to MODULE.bazel (bzlmod).