Remove alembic migrations for mautrix-facebook

They're gone now: b8ce80e476

roles/matrix-bridge-mautrix-facebook/templates/systemd/matrix-mautrix-facebook.service.j2

@@ -16,20 +16,6 @@ Environment="HOME={{ matrix_systemd_unit_home_path }}"
 ExecStartPre=-{{ matrix_host_command_sh }} -c '{{ matrix_host_command_docker }} kill matrix-mautrix-facebook 2>/dev/null'
 ExecStartPre=-{{ matrix_host_command_sh }} -c '{{ matrix_host_command_docker }} rm matrix-mautrix-facebook 2>/dev/null'
 
-# This bridge uses another mechanism for migrations now (migrations happen automatically during regular startup),
-# so going forward, running this alembic stuff will not necessary.
-# People who are upgrading from an older version of the bridge should go through this migration
-# first though, so we're keeping it around for now.
-ExecStartPre={{ matrix_host_command_docker }} run --rm --name matrix-mautrix-facebook-db \
-			--log-driver=none \
-			--user={{ matrix_user_uid }}:{{ matrix_user_gid }} \
-			--cap-drop=ALL \
-			--network={{ matrix_docker_network }} \
-			-v {{ matrix_mautrix_facebook_config_path }}:/config:z \
-			-v {{ matrix_mautrix_facebook_data_path }}:/data:z \
-			{{ matrix_mautrix_facebook_docker_image }} \
-			alembic -x config=/config/config.yaml upgrade head
-
 # Intentional delay, so that the homeserver (we likely depend on) can manage to start.
 ExecStartPre={{ matrix_host_command_sleep }} 5