Add metric triggerer_heartbeat

[vincbeck]

Create and emit a new metric triggerer_heartbeat.

I manually verified that the metric is emitted and its value being incrementally increased.

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[o-nikolas]

Looks good, any screenshots or confirmation from manual testing that the metric is being emitted? Could add it to the description if so!

[vincbeck]

Looks good, any screenshots or confirmation from manual testing that the metric is being emitted? Could add it to the description if so!

I did not take a screenshot but I tested the metric is emitted and its value getting incrementally increased. I used the option --integration otel in order to do so

[shubham22]

@hussein-awala - is it possible to include this in 2.7.x? It would be helpful for all customers adopting deferrables as Triggerer is a critical service, like Scheduler.

[potiuk]

@hussein-awala - is it possible to include this in 2.7.x? It would be helpful for all customers adopting deferrables as Triggerer is a critical service, like Scheduler.

IMHO I think we can treat it as bugfix - missing metrics that should have been there already :D

[eladkal]

I set it to 2.7.1 but final judgement call is for the release manager for that version