Remove ansible<2.2 apt cache hack

Now ansible apt module correctly behaves, so it's time
to deprecate these cruft tasks for apt.

Change-Id: Idea4d6beda9b0c62dc15de9f6d8dac7f12f050f9

tasks/galera_install_apt.yml

@@ -13,27 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-#TODO(evrardjp): Replace the next 2 tasks by a standard apt with cache
-#when https://github.com/ansible/ansible-modules-core/pull/1517 is merged
-#in 1.9.x or we move to 2.0 (if tested working)
-- name: Check apt last update file
-  stat:
-    path: /var/cache/apt
-  register: apt_cache_stat
-  tags:
-    - galera-apt-packages
-
-- name: Update apt if needed
-  apt:
-    update_cache: yes
-  when: "ansible_date_time.epoch|float - apt_cache_stat.stat.mtime > {{cache_timeout}}"
-  tags:
-    - galera-apt-packages
-
 - name: Install galera apt pre packages
   apt:
     pkg: "{{ item }}"
     state: "{{ galera_server_package_state }}"
+    update_cache: yes
+    cache_valid_time: "{{ cache_timeout }}"
   register: install_packages
   until: install_packages|success
   retries: 5
@@ -119,29 +104,12 @@
   tags:
     - galera-config
 
-#TODO(evrardjp): Replace the next 2 tasks by a standard apt with cache
-#when https://github.com/ansible/ansible-modules-core/pull/1517 is merged
-#in 1.9.x or we move to 2.0 (if tested working)
-- name: Check apt last update file
-  stat:
-    path: /var/cache/apt
-  register: apt_cache_stat
-  tags:
-    - galera-apt-packages
-
-- name: Update apt if needed
-  apt:
-    update_cache: yes
-  when: >
-    "ansible_date_time.epoch|float - apt_cache_stat.stat.mtime > {{cache_timeout}}" or
-    add_repos | changed
-  tags:
-    - galera-apt-packages
-
 - name: Install galera packages
   apt:
     pkg: "{{ item }}"
     state: "{{ galera_server_package_state }}"
+    update_cache: yes
+    cache_valid_time: "{{ add_repos | changed | ternary('0', cache_timeout) }}"
   register: install_packages
   until: install_packages|success
   retries: 5