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

java/google/registry/flows/StatelessRequestSessionMetadata.java

@@ -20,17 +20,14 @@ import java.util.Set;
 public class StatelessRequestSessionMetadata extends SessionMetadata {
 
   private final String clientId;
-  private final boolean isSuperuser;
   private final Set<String> serviceExtensionUris;
   private final SessionSource sessionSource;
 
   public StatelessRequestSessionMetadata(
       String clientId,
-      boolean isSuperuser,
       Set<String> serviceExtensionUris,
       SessionSource source) {
     this.clientId = clientId;
-    this.isSuperuser = isSuperuser;
     this.serviceExtensionUris = serviceExtensionUris;
     this.sessionSource = source;
   }
@@ -40,11 +37,6 @@ public class StatelessRequestSessionMetadata extends SessionMetadata {
     return clientId;
   }
 
-  @Override
-  public boolean isSuperuser() {
-    return isSuperuser;
-  }
-
   @Override
   public Set<String> getServiceExtensionUris() {
     return serviceExtensionUris;