Optimize uninstall tasks a bit

- forego removing Docker images - it's not effective anyway, because it
  only removes the last version.. which is a drop in the bucket, usually

- do not reload systemd - it's none of our business. `--tags=start`,
  etc., handle this

- combine all uninstall tasks under a single block, which only runs if
  we detect traces (a leftover systemd .service file) of the component.
  If no such .service is detected, we skip them all. This may lead to
  incorect cleanup in rare cases, but is good enough for the most part.

roles/custom/matrix-coturn/tasks/setup_uninstall.yml

@@ -6,42 +6,33 @@
   register: matrix_coturn_service_stat
   when: "not matrix_coturn_enabled | bool"
 
-- name: Ensure matrix-coturn is stopped
-  ansible.builtin.service:
-    name: matrix-coturn
-    state: stopped
-    enabled: false
-    daemon_reload: true
-  when: "matrix_coturn_service_stat.stat.exists | bool"
+- when: matrix_coturn_service_stat.stat.exists | bool
+  block:
+    - name: Ensure matrix-coturn is stopped
+      ansible.builtin.service:
+        name: matrix-coturn
+        state: stopped
+        enabled: false
+        daemon_reload: true
 
-- name: Ensure matrix-coturn-reload.timer is stopped
-  ansible.builtin.service:
-    name: matrix-coturn
-    state: stopped
-    enabled: false
-    daemon_reload: true
-  failed_when: false
-  when: "matrix_coturn_service_stat.stat.exists | bool"
+    - name: Ensure matrix-coturn-reload.timer is stopped
+      ansible.builtin.service:
+        name: matrix-coturn
+        state: stopped
+        enabled: false
+        daemon_reload: true
+      failed_when: false
 
-- name: Ensure systemd units don't exist
-  ansible.builtin.file:
-    path: "{{ devture_systemd_docker_base_systemd_path }}/{{ item }}"
-    state: absent
-  register: matrix_coturn_systemd_unit_uninstallation_result
-  with_items:
-    - matrix-coturn.service
-    - matrix-coturn-reload.service
-    - matrix-coturn-reload.timer
+    - name: Ensure systemd units don't exist
+      ansible.builtin.file:
+        path: "{{ devture_systemd_docker_base_systemd_path }}/{{ item }}"
+        state: absent
+      with_items:
+        - matrix-coturn.service
+        - matrix-coturn-reload.service
+        - matrix-coturn-reload.timer
 
-- name: Ensure systemd reloaded after unit removal
-  ansible.builtin.service:
-    daemon_reload: true
-  when: "matrix_coturn_systemd_unit_uninstallation_result.changed | bool"
-
-- name: Ensure Matrix coturn paths don't exist
-  ansible.builtin.file:
-    path: "{{ matrix_coturn_base_path }}"
-    state: absent
-
-# Intentionally not removing the Docker image when uninstalling.
-# We can't be sure it had been pulled by us in the first place.
+    - name: Ensure Matrix coturn paths don't exist
+      ansible.builtin.file:
+        path: "{{ matrix_coturn_base_path }}"
+        state: absent