[Observability] [Alert] Use alert state to store grouping object

[benakansara]

We need to use alert state to store grouping object (similar to #213550) that will be used to populate context.grouping variable for recovered alerts. Currently we are parsing instance id to form grouping object which can give wrong results if group values themselves contain ",".

Rules where this change needs to happen:

• Custom threshold rule
• APM Latency threshold rule
• APM Failed transaction rate rule
• APM Error count rule
• Log threshold rule

[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)

[maryam-saeidi]

Hi Bena,
What do you think about using kibana.alert.group or, in the future, kibana.alert.grouping for this purpose instead of saving it in the alert state?

[benakansara]

agree, ideally we should use kibana.alert.grouping and that was my initial idea as well, but I didn't know when are we going to prioritize that effort, so in the meantime I found this alternative of using alert state. Now that we have started adding kibana.alert.grouping to alerts, I would suggest to use that for context variable in the same PR as adding kibana.alert.grouping, wdyt? (it will save some time needed for testing and reviews)