Make tests for group membership more readable

roles/lmn_network/tasks/main.yml

@@ -7,7 +7,7 @@
       https_proxy="{{ proxy }}"
       ftp_proxy="{{ proxy }}"
       no_proxy="{{ no_proxy }}"
-  when: not (groups.teacherlaptop is defined and inventory_hostname in groups.teacherlaptop)
+  when: "'teacherlaptop' not in group_names"
 
 - name: Set aptcache
   ansible.builtin.copy:
@@ -27,4 +27,4 @@
       deb http://deb.debian.org/debian/ {{ ansible_distribution_release }}-proposed-updates
       main non-free-firmware
     state: present
-  when: groups.R202 is defined and inventory_hostname in groups.R202
+  when: "'R202' in group_names"