chore: Remove skipping google-cloud-java

Author: lqiu96

.kokoro/nightly/downstream-protobuf-binary-compatibility.sh

@@ -36,12 +36,6 @@ mvn -B -ntp clean compile
 pushd dependencies
 
 for repo in ${REPOS_UNDER_TEST//,/ }; do # Split on comma
-  # Skip the GAPIC monorepo as it's autogenerated
-  # TODO(lawrenceqiu): Test using the showcase module for GAPIC coverage
-  if [[ "$repo" == "google-cloud-java" ]]; then
-    continue
-  fi
-
   # Perform source-compatibility testing on main (latest changes)
   git clone "https://github.com/googleapis/$repo.git" --depth=1
   pushd "$repo"
@@ -69,4 +63,4 @@ for repo in ${REPOS_UNDER_TEST//,/ }; do # Split on comma
   done
 done
 popd
-popd
+popd