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.

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

javatests/google/registry/flows/FlowRunnerTest.java

@@ -69,7 +69,6 @@ public class FlowRunnerTest extends ShardableTestCase {
 
     final EppOutput eppOutput = mock(EppOutput.class);
     EppResponse eppResponse = mock(EppResponse.class);
-    when(eppResponse.getCreatedRepoId()).thenReturn("foo");
     when(eppResponse.getExecutionTime()).thenReturn(new DateTime(1337));
     when(eppOutput.getResponse()).thenReturn(eppResponse);