Delete the check_cue_response Cloud Function

[troyraen]

I think we can ignore this cloud function here. I'd like to just delete it. It used to do several checks on whether things were running properly and generate a notification/alarm if they weren't. But most (I think all) have become unnecessary over time. Some kind of check/alarm system might be useful, but I don't think there's anything about this one that we should salvage.

Originally posted by @troyraen in #216 (comment)

I think the steps to delete it are:

• Delete its directory.
• Find and remove it from the docs.
• Delete the deployed instance. I don't think it's even been triggered in a long time, but we should check which topic it's connect to and delete that too if not being used.