Contextual attributes for Log Threshold Rule

[benakansara]

Part of https://github.com/elastic/actionable-observability/issues/7

• Provide contextual attributes to active and recovered alerts based on group by and filter used when creating a Log threshold rule
• Index new context variables to AAD

When the prefix of group by or filter includes one of the following, add contextual attributes for that entity.

• cloud
• host
• orchestrator
• container
• labels
• tags

Exclude following metrics attributes from the context:

• *.cpu.*
• *.disk.*
• *.network.*
• *.memory.*

[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)