`increment_auto_off.py` is difficult to sustain

[SteveMicroNova]

if this is a copy of any section of the code, you should probably create a function out of it and call it from both places

Originally posted by @rtertiaer in https://github.com/micro-nova/AmpliPi/pull/828#discussion_r1795608503

Ryan is right here, pay down the tech debt of copying endpoints line for line; make them importable from /usr/local/bin/increment_auto_off.py

I attempted to do this using a symbolic link and relative import, ran into an issue where increment_auto_off.py isn't inside the venv and so doesn't have access to all required dependencies and wasn't able to make said dependencies install globally via configure.py either