Remove "waiting for can interfaces" and "found all can interfaces" message from robot systemd definition

[ThadHouse]

We're switching to use journald to read robot logs, which means these show up.

Ideally, this whole check should be done using another method, that isn't ran each time the robot starts up.

[auscompgeek]

Could we either Requires= or BindsTo= the corresponding .device units? Either in a .target or directly in robot.service.

[rzblue]

Ideally, this whole check should be done using another method, that isn't ran each time the robot starts up.

if the CAN interfaces are managed with systemd-networkd, this is really easy. The loop in the robot service script is a hack to work around lack of ordering.