Use consumeErrors=True on all DeferredLists.

This is so that the DeferredLists actually consume the error instead of
propogating down the non-existent errback chain. This should reduce the
number of unhandled errors we are seeing.

synapse/federation/federation_server.py

@@ -124,7 +124,7 @@ class FederationServer(FederationBase):
                         edu.content
                     )
 
-            results = yield defer.DeferredList(dl)
+            results = yield defer.DeferredList(dl, consumeErrors=True)
 
         ret = []
         for r in results: