Monitor for transcriptions that are stuck "in progress" for more than a few minutes

[daguar]

From digging into the logs when our current monitoring has found issues, this is the best concrete marker that the Twilio transcription API is having issues.

It has the added benefit of having far fewer false positives (though being less close to the TRUE user story of our current monitoring which is that everyone should receive a response within a few minutes.)

If this is implemented, we'll keep both on, but use this one (with distinct EngineLight message) as key for contacting Twilio support about an outage.