Do not use ‘yes/no’ for boolean values (#11472)

Consistent boolean values in ansible playbooks

roles/bootstrap-os/tasks/amzn.yml

@@ -8,9 +8,9 @@
     file: epel
     description: Extra Packages for Enterprise Linux 7 - $basearch
     baseurl: http://download.fedoraproject.org/pub/epel/7/$basearch
-    gpgcheck: yes
+    gpgcheck: true
     gpgkey: http://download.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-7
-    skip_if_unavailable: yes
-    enabled: yes
-    repo_gpgcheck: no
+    skip_if_unavailable: true
+    enabled: true
+    repo_gpgcheck: false
   when: epel_enabled