Fix conditional check of string variable

roles/lmn_misc/tasks/main.yml

@@ -98,7 +98,7 @@
       export superusers
       password_pbkdf2 root {{ grub_pwd }}
   notify: Run update-grub
-  when: grub_pwd | bool | default(false)
+  when: grub_pwd is defined and grub_pwd is truthy
 
 - name: Allow booting grub menu entries
   ansible.builtin.lineinfile:

roles/lmn_network/tasks/main.yml

@@ -5,14 +5,14 @@
     mode: '0644'
     content: >
       {{ apt_conf }}
-  when: apt_conf | bool | default(false)
+  when: apt_conf is defined and apt_conf is truthy
 
 - name: Set NTP server
   ansible.builtin.lineinfile:
     path: /etc/systemd/timesyncd.conf
     insertafter: '^#NTP='
     line: NTP={{ ntp_serv }}
-  when: ntp_serv | bool | default(false)
+  when: ntp_serv is defined and ntp_serv is truthy
 
 - name: Add proposed-updates repository
   ansible.builtin.apt_repository: