lint: don't compare to literal true/false

Fix ansible lint 601 error:

[601] Don't compare to literal True/False
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>

infrastructure-playbooks/purge-cluster.yml

@@ -791,7 +791,7 @@
       state: absent
     when:
       - ansible_pkg_mgr == 'yum'
-      - purge_all_packages == true
+      - purge_all_packages | bool
 
   - name: purge extra packages with dnf
     dnf:
@@ -799,7 +799,7 @@
       state: absent
     when:
       - ansible_pkg_mgr == 'dnf'
-      - purge_all_packages == true
+      - purge_all_packages | bool
 
   - name: purge extra packages with apt
     apt:
@@ -807,7 +807,7 @@
       state: absent
     when:
       - ansible_pkg_mgr == 'apt'
-      - purge_all_packages == true
+      - purge_all_packages | bool
 
   - name: remove config and any ceph socket left
     file: