Let systemd check kernel command line options

[bwarden]

Cleanup for clr-installer-provision.service. Trying to avoid extra embedded bash calls -- use systemd's internal capabilties instead of relying on bashisms.

Fixes Issue: #

Changes proposed in this pull request:

• Avoid using bash calls as much as possible
• Use systemd's built-in ConditionKernelCommandLine directive to detect clri.descriptor to decide whether to run
• Allow this unit to take over the console (was blocking, attempting askpass, while getty was active)
• Call cat directly to print /etc/issue to console (instead of from bash)
• Call clr-installer directly instead of from a bash loop -- should implement retries via systemd's mechanisms instead
• Call reboot directly as a post action only if/after the installer succeeded

[bryteise]

Seems fairly reasonable to me.

[ahkok]

It looks fine and a lot cleaner. I'm not sure if we want to Restart=on-failure since the default value for that is no and it will reboot the system immediately? I would definitely experiment with making clr-installer fail and see whether at a minimum there is some usable output before the system reboots.

But aside that this is a good cleanup.

[bwarden]

Also, the console blocking failures I was seeing are possibly because I was on ttyS1, which isn't listed in Conflicts. Worth further testing in a controlled environment.