Remove double exceptin handling that causes false replica failures

we already fail the shard in the `onFailure` method if the replica
operation barfs. This additional check has been added lately that
bypasses the clusterstate observer which causes replicas to fail
if the mappings are not yet present.

src/main/java/org/elasticsearch/action/support/replication/TransportShardReplicationOperationAction.java

@@ -278,9 +278,6 @@ public abstract class TransportShardReplicationOperationAction<Request extends S
         protected void doRun() throws Exception {
             try (Releasable shardReference = getIndexShardOperationsCounter(request.internalShardId)) {
                 shardOperationOnReplica(request.internalShardId, request);
-            } catch (Throwable t) {
-                failReplicaIfNeeded(request.internalShardId.index().name(), request.internalShardId.id(), t);
-                throw t;
             }
             channel.sendResponse(TransportResponse.Empty.INSTANCE);
         }