Put Kiwix var {{ systemctl_program }} to rest — simple is almost always better

[holta]

Unclear that systemctl really needs a full path but it can't hurt.

Tested on Ubuntu 23.04's latest daily, with this PR using canonical path /usr/bin/systemctl to be consistent with command-line usage.

Building on:

• PR Put vars/<OS-VER>.yml files on a diet, moving stale vars to default_vars.yml or roles/X/defaults #3440
• IIAB 8.0 fails to install on Pi 4 running Desktop version 2022-09-22-raspios-bullseye-arm64.img on PI 4 #3444

[jvonau]

Or just alter the crontab stanza to actually use systemctl_program, touches one file instead of 3 files. Might also want to update to the cron ansble plugin in place of lineinfile like matomo uses.

[jvonau]

Guess I should of asked if the 4am restart of kiwix is even still required as this was originally a cheap workaround to keep kiwix running from years ago. #484 #485 XSCE/xsce@2a62885

[jvonau]

Perhaps there could be a new variable that could enable the cron routine on demand in place of just restarting as I think that wipes out the cache of search history that was built up within kiwix-serve.

[holta]

Guess I should of asked if the 4am restart of kiwix is even still required as this was originally a cheap workaround to keep kiwix running from years ago. #484 #485 XSCE/xsce@2a62885

kiwix-serve has very regular bugs as it make strides evolving + improving, as part of a continual community process, which cannot be fully predicted one month to the next. As such the 4AM reboot serves to help protect communities/schools/users on a valuable ongoing basis.