Use ansible_facts to reference facts

By default, Ansible injects a variable for every fact, prefixed with
ansible_. This can result in a large number of variables for each host,
which at scale can incur a performance penalty. Ansible provides a
configuration option [0] that can be set to False to prevent this
injection of facts. In this case, facts should be referenced via
ansible_facts.<fact>.

This change updates all references to Ansible facts from using
individual fact variables to using the items in the
ansible_facts dictionary. This allows users to disable fact variable
injection in their Ansible configuration, which may provide some
performance improvement.

[0] https://docs.ansible.com/ansible/latest/reference_appendices/config.html#inject-facts-as-vars

tasks/centos.yml

@@ -6,7 +6,7 @@
   become: true
 
 - include_tasks: amazon.yml
-  when: ansible_system_vendor == 'Amazon EC2'
+  when: ansible_facts.system_vendor == 'Amazon EC2'
 
 - name: centos | installing sg3_utils
   package: