Replaced hard coded string with identifier variable

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

group_vars/matrix_servers

@@ -2671,7 +2671,7 @@ matrix_nginx_proxy_proxy_matrix_identity_api_addr_with_container: "matrix-ma1sd:
 matrix_nginx_proxy_proxy_matrix_identity_api_addr_sans_container: "127.0.0.1:{{ matrix_ma1sd_container_port }}"
 
 matrix_nginx_proxy_proxy_media_repo_enabled: "{{ matrix_media_repo_enabled }}"
-matrix_nginx_proxy_proxy_media_repo_addr_with_container: "matrix-media-repo:{{ matrix_media_repo_port }}"
+matrix_nginx_proxy_proxy_media_repo_addr_with_container: "{{ matrix_media_repo_identifier }}:{{ matrix_media_repo_port }}"
 matrix_nginx_proxy_proxy_media_repo_addr_sans_container: "127.0.0.1:{{ matrix_media_repo_port }}"
 
 # By default, we do TLS termination for the Matrix Federation API (port 8448) at matrix-nginx-proxy.