Comment 0 for bug 1814116

BUG DESCRIPTION
===
I'm using latest master of tripleo-quickstart, this implies containerized undercloud.
Running the quickstart (not featureset related), with an arbitrary number of nodes which
of course involve 3 controllers, when the overcloud-deploy role is reached, it fails
because the ntp_server parameter is missing unless user define it (or override it) in a
custom_env yaml file that should be passed to the quickstart execution.

Since the operator can override this value providing the ntp_server variable, the error
is caused if the user doesn't specify this parameter in an env.yaml because a default
value is missed, causing the following error during the *overcloud deploy* execution:

https://pastebin.com/hLfLCk5S

In a scenario with `controllers > 1` this value is relevant and the overcloud-deploy role
in the controller sections has a couple of tasks for configuring correctly chrony (as
described here https://docs.openstack.org/install-guide/environment-ntp.html), so this value
is expected to be found.

Further, this value is used by the pre-deploy task to set a fact which will be used by the
PLAYBOOK NAME to build the overcloud-deploy.sh script (a j2 template).

This cause the stop with an error of the the overcloud-deploy playbook (that has a task to
build this bash script), and the operator has to patch manually that script to deploy the
overcloud.

How to reproduce the error:
--
Using quickstart just deploy an overcloud with 3ctrl_1comp or 3ctrl_1comp_3ceph
using featureset049 for the ceph deployment scenario, feature001 for the rest; of
course, you can your preferred featureset

Some considerations
---

This parameter is featureset independent, it make sense in a deployment scenario in
which services need to be synchronized (it means controllers > 1), so this parameter
should go on all the node files affected by this issue.
The second consideration is related to the default that we should assign to the
variable.
As done for the undercloud, the default could be pool.ntp.org, if some scenarios need
a change (i.e. install behind a proxy), the operator can ovveride the parameter.

SOME TEST CASES TO CONFIRM THE ISSUE:
==
1. quickstart with 3ctrl_1comp + featureset001 => Verified
2. quickstart with 3ctrl_2comp_3ceph + featureset049 => Verified
3. quickstart with 3ctrl_ + featureset001 => Verified
4. quickstart with 1ctrl_1comp + featureset001 => IT DOESN'T HAPPEN AS EXPECTED
5. quickstart with 3ctrl_3comp + any featureset => VERIFIED