Clean up inithooks

[JedMeister]

firstboot.d bash inithook updates:

• apply shellcheck fixes
• remove redundant comments & code
• improve readability
• other minor tweaks

bin python inithook update:

• add missing schema to cli options (included in help, but not in getopt options)
• GL password setting output as string (not binary string)
• GL password setting output to relevant stream - i.e. error to stderr

[OnGle]

Lgtm!

(Big 👍 for replacing some ternary control flow with an if statement)