Fix Incorrect Opsgenie Tags Formatting

[abhishekjiitr]

When there are multiple matches in a single run of ElastAlert and the Opsgenie Tags are dynamic (deriving value from matching documents) then when the tag field for each unique alert is formatted only from the values of the first match. e.g.

Input:

opsgenie_tags: ["user"]
matches: ["alice", "bob"]

Expected Alerts:

Alert1: opsgenie_tags: ["alice"]
Alert2: opsgenie_tags: ["bob"]

Actual Alerts:

Alert1: opsgenie_tags: ["alice"]
Alert2: opsgenie_tags: ["alice"]

Fix

Instead of formatting a tag and changing its value in the entire objects state(self.tags), make a new variable that stores the formatted value, and directly add it to the post object that will be sent by the Opsgenie Alerter.