Don't to_json the matrix_synapse_database_password

It's good policy to use ansible vault to define passwords. However, due to an Ansible bug, to_json will not cause the password to be decrypted: https://github.com/ansible/ansible/issues/24425

roles/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -327,7 +327,7 @@ database:
   name: "psycopg2"
   args:
     user: {{ matrix_synapse_database_user|to_json }}
-    password: {{ matrix_synapse_database_password|to_json }}
+    password: {{ matrix_synapse_database_password }}
     database: "{{ matrix_synapse_database_database }}"
     host: "{{ matrix_synapse_database_host }}"
     cp_min: 5