terminalserver: Replace deprecated apt_key module

terminalserver/tasks/x2go.yml

 ---
 
 - name: ensure apt key for x2go is present
-  apt_key:
-    keyserver: keys.gnupg.net
-    id: E1F958385BFE2B6E
-    state: present
-  notify:
-    - update apt cache
+  copy:
+    src: x2go-archive-debian-ubuntu-signing-key.gpg
+    dest: /etc/apt/trusted.gpg.d
+    owner: root
+    group: root
+    mode: "0644"
+    # Install only if it does not exist yet, this file will get overridden by
+    # the x2go-keyring package
+    force: false
   tags:
     - x2go
     - repos