Removes sysctl_set parameter from RHEL sysctl task

It appears that the sysctl_set parameter overrides ignorerrors. Since we
fully expect `kernel.exec_shield` to be handled differently on CentOS
7+, where it is is no longer configurable, let's preserve the
functionality provided by ignorerrors.

Author: Conor Schaefer

tasks/sysctl.yml

@@ -29,7 +29,6 @@
   sysctl:
     name: '{{ item.key }}'
     value: '{{ item.value }}'
-    sysctl_set: yes
     state: present
     reload: yes
     ignoreerrors: yes