Remove unused `matrix_element_call_metrics_*` variables

roles/custom/matrix-element-call/defaults/main.yml

@@ -134,10 +134,6 @@ matrix_element_call_floc_optout_enabled: false
 # See: `matrix_element_call_http_header_strict_transport_security`
 matrix_element_call_hsts_preload_enabled: false
 
-# Enable or disable metrics collection
-matrix_element_call_metrics_enabled: false
-matrix_element_call_metrics_port: 2112
-
 # Controls the default_server_config/m.homeserver/base_url property in the config.json file.
 matrix_element_call_config_default_server_config_m_homeserver_base_url: "{{ matrix_homeserver_url }}"