Automatically do the right thing with regards to Synapse Metrics htpasswd

.. regardless of whether matrix-nginx-proxy runs in a container or not

roles/matrix-nginx-proxy/defaults/main.yml

@@ -221,7 +221,7 @@ matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_enabled: false
 # e.g. `htpasswd -c mypass.htpasswd prometheus` and enter `mysecurepw` when prompted yields `prometheus:$apr1$wZhqsn.U$7LC3kMmjUbjNAZjyMyvYv/`
 # The part after `prometheus:` is needed here. matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_key: "$apr1$wZhqsn.U$7LC3kMmjUbjNAZjyMyvYv/"
 matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_key: ""
-matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_path: "/nginx-data/matrix-synapse-metrics-htpasswd"
+matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_path: "{{ matrix_nginx_proxy_data_path_in_container if matrix_nginx_proxy_enabled else matrix_nginx_proxy_data_path }}/matrix-synapse-metrics-htpasswd"
 
 # The addresses where the Matrix Client API is.
 # Certain extensions (like matrix-corporal) may override this in order to capture all traffic.