[APM] Latency threshold rule type should differentiate buckets on multiple terms

[ogupte]

A recent fix to the latency threshold rule type allows users who select "Environment: All" to differentiate between each environments for the selected aggregation type, instead of lumping them all into one bucket. This partially fixes the this rule type since the same should be done for the other dimensions where a user can select "All":

• Service name
• Transaction type

These fields, along with service environment, need to be included in a multiterms bucket aggregation since any combination among these dimensions each can trigger their own alert.

The query should also conditionally apply each of these params as terms filters if a specific param is selected on rule creation.