Only download Grafana dashboard URLs for enabled services

If someone is using Dendrite and enabling Grafana, we'll no longer
download Synapse dashboards.

If someone is not using node-exporter, we'll no longer download node
exporter dashboards.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2133

roles/matrix-grafana/tasks/setup.yml

@@ -68,7 +68,7 @@
     mode: 0440
     owner: "{{ matrix_user_username }}"
     group: "{{ matrix_user_groupname }}"
-  with_items: "{{ matrix_grafana_dashboard_download_urls_all }}"
+  with_items: "{{ matrix_grafana_dashboard_download_urls }}"
   when: matrix_grafana_enabled | bool
   register: result
   retries: "{{ matrix_geturl_retries_count }}"

roles/matrix-grafana/tasks/validate_config.yml

@@ -5,3 +5,12 @@
     msg: >
       You need to enable `matrix_prometheus_enabled` to use Prometheus as data source for Grafana.
   when: "not matrix_prometheus_enabled"
+
+- name: (Deprecation) Catch and report renamed settings
+  ansible.builtin.fail:
+    msg: >-
+      Your configuration contains a variable, which now has a different name.
+      Please change your configuration to rename the variable (`{{ item.old }}` -> `{{ item.new }}`).
+  when: "item.old in vars"
+  with_items:
+    - {'old': 'matrix_grafana_dashboard_download_urls_all', 'new': 'matrix_grafana_dashboard_download_urls'}