matrix: Update homeserver config from sample_config.yaml

roles/matrix/templates/homeserver.yaml.j2

@@ -109,7 +109,7 @@ allow_public_rooms_over_federation: true
 # For example, for room version 1, default_room_version should be set
 # to "1".
 #
-#default_room_version: "5"
+#default_room_version: "6"
 
 # The GC threshold parameters to pass to `gc.set_threshold`, if defined
 #
@@ -895,7 +895,7 @@ media_store_path: "/var/lib/synapse/media_store"
 
 # The largest allowed upload size in bytes
 #
-max_upload_size: 30M
+#max_upload_size: 50M
 
 # Maximum number of pixels that will be thumbnailed
 #