Remove GitRepositoryManager#openMetadataRepository

We were originally going to use this for a less-risky migration of
googlesource.com data. Our current migration plan no longer calls for
this, so let's get rid of the complexity. As far as
LocalDiskRepositoryManager goes, we don't expect anybody to need to
enable this before we feel pretty good about the behavior in the same
repo.

Change-Id: I99c7218a190d634ff31e8293f592f75f47a50724

gerrit-server/src/main/java/com/google/gerrit/server/notedb/RepoSequence.java

@@ -129,7 +129,7 @@ public class RepoSequence {
   }
 
   private void acquire() throws OrmException {
-    try (Repository repo = repoManager.openMetadataRepository(projectName);
+    try (Repository repo = repoManager.openRepository(projectName);
         RevWalk rw = new RevWalk(repo)) {
       TryAcquire attempt = new TryAcquire(repo, rw);
       RefUpdate.Result result = retryer.call(attempt);