Decouple superuser from SessionMetadata

Superuser should only be settable via the tool (see []
which is merged in here but not diffbased, and which removes
the implicit superuser for CharlestonRoad). It is a property
of the request, not of the session (there are no sessions in the tool).
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=125204707

javatests/google/registry/flows/domain/DomainRestoreRequestFlowTest.java

@@ -369,7 +369,6 @@ public class DomainRestoreRequestFlowTest extends
   @Test
   public void testSuccess_superuserUnauthorizedClient() throws Exception {
     thrown.expect(ResourceNotOwnedException.class);
-    sessionMetadata.setSuperuser(true);
     sessionMetadata.setClientId("NewRegistrar");
     persistPendingDeleteDomain();
     runFlowAssertResponse(readFile("domain_update_response.xml"));