Unmark Gitaly features as OPT_OUT until the gRPC proxy issue is fixed

lib/gitlab/git/repository.rb

@@ -126,7 +126,7 @@ module Gitlab
       end
       def exists?
-        Gitlab::GitalyClient.migrate(:repository_exists, status: Gitlab::GitalyClient::MigrationStatus::OPT_OUT) do |enabled|
+        Gitlab::GitalyClient.migrate(:repository_exists) do |enabled|
           if enabled
             gitaly_repository_client.exists?
           else
@@ -188,7 +188,7 @@ module Gitlab
       end
       def local_branches(sort_by: nil)
-        gitaly_migrate(:local_branches, status: Gitlab::GitalyClient::MigrationStatus::OPT_OUT) do |is_enabled|
+        gitaly_migrate(:local_branches) do |is_enabled|
           if is_enabled
             gitaly_ref_client.local_branches(sort_by: sort_by)
           else