Incorrect setup of Systemd restart value

[andrejzelnik]

Proposed changes

This PR is intended as the fix for incorrect setup of systemd Restart value.

Current handling of the value within nginx.service.override.conf.j2:

...
{% if nginx_service_restartonfailure is defined %}
Restart=on-failure
{% endif %}
...

nginx_service_restartonfailure variable is not defined or mentioned in whole repository, but will keep its usage for backward compatibility and possible use of external value.

My proposed change works with nginx_service_restart variable that is already prepared in systemd.yml variable file:

...
# Set the restart policy for systemd systems
# Values = no (default), on-failure, on-abnormal, on-watchdog, on-abort, always
# [Service]
# Restart=on-failure
# Default is to comment this out
# nginx_service_restart: on-failure
...

Checklist

• I have read the CONTRIBUTING document
• I have added Molecule tests that prove my fix is effective or that my feature works
• I have checked that all Molecule tests pass after adding my changes
• I have updated any relevant documentation (defaults/main/*.yml, README.md and CHANGELOG.md)

[alessfg]

Thanks for the PR! Somehow I missed this when reviewing the original service PR 😅