Remove more dead/broken dev scripts (#12355)

Author: David Robertson

changelog.d/12355.misc

@@ -0,0 +1 @@
+Remove broken and unused development scripts.

mypy.ini

@@ -24,11 +24,8 @@ files =
 exclude = (?x)
   ^(
    |scripts-dev/build_debian_packages.py
-   |scripts-dev/definitions.py
    |scripts-dev/federation_client.py
-   |scripts-dev/hash_history.py
    |scripts-dev/release.py
-   |scripts-dev/tail-synapse.py
 
    |synapse/_scripts/export_signing_key.py
    |synapse/_scripts/move_remote_media_to_new_store.py