rhel8: add default python bin path

rhel8: add default python bin path

On RHEL 8 system we should check the /usr/libexec/platform-python path
instead of installing python36 package.

[DEPRECATION WARNING]: Distribution redhat 8.0 on host xxxxx should use
/usr/libexec/platform-python, but is using /usr/bin/python for backward
compatibility with prior Ansible releases. A future Ansible release will
default to using the discovered platform python for this host.

Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>
(cherry picked from commit f90696c36e0a0cce57e61a66057b628267fdc3ed)