Use raw module to get Undercloud's python interpreter.
Use raw module to get Undercloud's python interpreter.

As an improvement of [0], as the delegate_to statement
does not fully work without having the right python
interpreter configured in the ansible_python_interpreter
variable. Even though if it's been executed from the
localhost node. We're trying an approach based on the
fact that the raw and script modules do not need to
have set the python interpreter. By disabling the facts
gathering, we are allowed to run the 'command -v python
/usr/libexec/platform-python' in the Undercloud even if
the Undercloud is running RHEL7.3, RHEL7.6 or RHEL8. And
once we get the right python interpreter we can pass
it for updating the inventory.

[0] - https://review.gerrithub.io/c/redhat-openstack/infrared/+/467487/

Change-Id: Ia097eb26e8d83d72870c0ec43ec95fa271913c61

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared