TuneD parameters in [sysctl] plug-in are not expanded in the logs

What were you trying to do that didn't work?

Scrape the logs for correct information.  Incorrect information is provided in the logs. Note that while this may seem trivial, we actually use the logs in OCP to provide status of k8s objects and because of the "Overriding ..." message we incorrectly set a profile as Degraded, which results in customer issues such as 03673569.

How reproducible:

Always.

Steps to reproduce

1. echo 'vm.max_map_count=1048576' > /etc/sysctl.d/50-vm-max-map-count.conf
2. Create the following TuneD profile:

[main]
summary=PoC

[sysctl]
vm.max_map_count = ${a}
[variables]
a=1048576

1. Start TuneD and select the profile above.
2. See the logs:
   2023-12-07 16:04:51,524 INFO     tuned.plugins.plugin_sysctl: reapplying system sysctl
   2023-12-07 16:04:51,524 INFO     tuned.plugins.plugin_sysctl: Overriding sysctl parameter 'vm.max_map_count' from '${a}' to '1048576'

Expected results

Correct information provided in the logs.  In the case above, no logs about "Overriding ..." should be logged.

Actual results

2023-12-07 16:04:51,524 INFO     tuned.plugins.plugin_sysctl: Overriding sysctl parameter 'vm.max_map_count' from '${a}' to '1048576'