autotest: add reasons to every delay_sim_time call

[peterbarker]

Summary

Puts reasons on each delay call

Classification & Testing (check all that apply and add your own)

• Checked by a human programmer
• Non-functional change
• No-binary change
• Infrastructure change (e.g. unit tests, helper scripts)
• Automated test(s) verify changes (e.g. unit test, autotest)
• Tested manually, description below (e.g. SITL)
• Tested on hardware
• Logs attached
• Logs available on request

Description

It's useful to be able to disambigaute delays and whatnot in the output.

This should also allow us to eliminate some of these calls when we can instead look for something in the telemetry stream instead.