roles/common: Remove snaps on Ubuntu 20.04

The list of pre-installed snaps and system packages is different on
Ubuntu 20.04 than it was in previous LTS releases.

See: https://www.kevin-custer.com/blog/disabling-snaps-in-ubuntu-20-04/

roles/common/tasks/packages_Ubuntu.yml

@@ -29,7 +29,21 @@
   - name: Install base packages
     apt: pkg={{ ubuntu_base_packages }} state=present update_cache=yes cache_valid_time=3600
 
-  - name: Set fact for packages to remove
+  # We have to remove snaps one by one in a specific order because some depend
+  # on others. Only after that can we remove the corresponding system packages.
+  - name: Remove lxd snap
+    snap: name=lxd state=absent
+    when: ansible_distribution_version is version('20.04', '==')
+
+  - name: Remove core18 snap
+    snap: name=core18 state=absent
+    when: ansible_distribution_version is version('20.04', '==')
+
+  - name: Remove snapd snap
+    snap: name=snapd state=absent
+    when: ansible_distribution_version is version('20.04', '==')
+
+  - name: Set fact for packages to remove (Ubuntu <= 18.04)
     set_fact:
       ubuntu_annoying_packages:
         - whoopsie # security (CIS 4.1)
@@ -43,6 +57,19 @@
         - liblxc1 # annoying (Ubuntu >= 16.04)
         - lxc-common # annoying (Ubuntu >= 16.04)
         - lxcfs #annoying (Ubuntu >= 16.04)
+    when: ansible_distribution_version is version('18.04', '<=')
+
+  - name: Set fact for packages to remove (Ubuntu 20.04)
+    set_fact:
+      ubuntu_annoying_packages:
+        - whoopsie # security (CIS 4.1)
+        - apport   # security (CIS 4.1)
+        - command-not-found # annoying
+        - command-not-found-data # annoying
+        - python3-commandnotfound # annoying
+        - snapd # annoying (Ubuntu >= 16.04)
+        - lxd-agent-loader # annoying (Ubuntu 20.04)
+    when: ansible_distribution_version is version('20.04', '==')
 
   - name: Remove packages
     apt: name={{ ubuntu_annoying_packages }} state=absent purge=yes