Use apt module to run apt-get commands

Removes some warning messages from ansible output

roles/common/tasks/update_everything.yml

@@ -38,7 +38,6 @@
   tags: apt
 
 - name: Remove unneeded packages.
-  command: apt-get autoremove -y
-  register: autoremove_result
-  changed_when: "'0 upgraded' not in autoremove_result.stdout"
+  apt:
+    autoremove: yes
   tags: apt

roles/gitian/tasks/main.yml

@@ -203,9 +203,8 @@
     executable: /bin/bash
 
 - name: Clean the apt cache to free up space.
-  command: apt-get autoclean
-  register: autoclean_result
-  changed_when: "'Del' in autoclean_result.stdout"
+  apt:
+    autoclean: yes
 
 - include_tasks: gpg.yml
   tags: gpg