Description of problem:
HorizonDebug is not enabling debug log in horizon containers.

Version-Release number of selected component (if applicable):
16.1

How reproducible:
100%


Steps to Reproduce:
1. Deploy with the following envirnoment

~~~
parameter_defaults:
  HorizonDebug: True
~~~

2. Verify no debug log are emitted from horizon containers

Actual results:

~~~
$ vim var/lib/config-data/puppet-generated/horizon/etc/openstack-dashboard/local_settings

DEBUG = False
TEMPLATE_DEBUG = DEBUG

LOGGING = {
...
    'handlers': {
        'null': {
            'level': 'DEBUG',
            'class': 'logging.NullHandler',
        },
        'console': {
            # Set the level to "DEBUG" for verbose output logging.
            'level': 'INFO',
            'class': 'logging.StreamHandler',
        },
        'file': {
            'level': 'INFO', <===
            'class': 'logging.FileHandler',
            'filename': '/var/log/horizon/horizon.log',
            'formatter': 'verbose',
        },
    },
~~~

Expected results:

~~~
$ vim var/lib/config-data/puppet-generated/horizon/etc/openstack-dashboard/local_settings

DEBUG = False
TEMPLATE_DEBUG = DEBUG

LOGGING = {
...
    'handlers': {
        'null': {
            'level': 'DEBUG',
            'class': 'logging.NullHandler',
        },
        'console': {
            # Set the level to "DEBUG" for verbose output logging.
            'level': 'INFO',
            'class': 'logging.StreamHandler',
        },
        'file': {
            'level': 'DEBUG', <===
            'class': 'logging.FileHandler',
            'filename': '/var/log/horizon/horizon.log',
            'formatter': 'verbose',
        },
    },
~~~

Additional info:

This issue is being tracked upstream at [1].

This issue seems to be caused by two different issues:

- Heat template logic has a flaw, being addressed by [2] 
- horizon::log_level is not correctly set to "DEBUG", addressed by [3]


[1] https://bugs.launchpad.net/tripleo/+bug/1908362
[2] https://review.opendev.org/c/openstack/tripleo-heat-templates/+/767281
[3] https://review.opendev.org/c/openstack/tripleo-heat-templates/+/743441