Remove useless createdRepoId from logging

It is no longer needed since we don't do log-replay and it's
annoying to support in the flat flows.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135805088

java/google/registry/flows/ResourceCreateFlow.java

@@ -88,11 +88,6 @@ public abstract class ResourceCreateFlow
     modifyCreateRelatedResources();
   }
 
-  @Override
-  protected final String getCreatedRepoId() {
-    return newResource.getRepoId();
-  }
-
   /** Modify any other resources that need to be informed of this create. */
   protected void modifyCreateRelatedResources() {}