Description of problem:
I just upgraded my Sat 6.7 to 6.8 and noticed that after the upgrade, RHEL 7 hosts that I provision now get `ntp` instead of `chrony`.

It seems that in the template named "Kickstart default" the line

```
  use_ntp = host_param_true?('use-ntp') || (is_fedora && os_major < 16) || (rhel_compatible && os_major <= 7)
```

should read `< 7`, not `<= 7`, since in the RHEL 7 Admin guide ( https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-configuring_ntp_using_the_chrony_suite ) we recommend chrony for most use cases (quite rightly so IMNSHO).

Version-Release number of selected component (if applicable):
satellite-6.8.4-1.el7sat.noarch

How reproducible:
always

Steps to Reproduce:
1. have a soe-ci setup[1] that tests that chrony is set up correctly[2]
2. do nightly CI runs against a Satellite 6.7
3. test for chrony passes at every CI run
4. Upgrade Satellite to 6.8

Actual results:
The kickstart file rendered from the template named "Kickstart default" now reads
```
[...]
%packages

yum
dhclient
ntp
-chrony
wget
@Core
redhat-lsb-core


%end
[...]
```

Obviously that is not what I want, I would have liked the template to render in a way that does NOT force chrony out and ntp in, just like 6.7 seems to have done.

Expected results:
Satellite 6.8's default provisioning template for kickstart installs continues rolling out the preferred chrony

Additional info:
[1] https://github.com/RedHatSatellite/soe-ci/
[2] the test in question is just a primitive bats test that
- checks for the presence of the RPM `chrony`
- does a `systemctl status chronyd` and expects a return code of 0
- does a `chronyc sources` and checks that the system under test is using at least 2 servers

I only caught this changed behaviour because that test is run each night.