Removed event_id property from config

Event_id was used in some of the stacktach smoke tests,
but it was very cumbersome to keep updating the event_id every
month as the data gets purged after 30 days. Hence, removing it
from here & updated tests with a new method

Change-Id: Id33a29576391779818efd510608f95c93eeb79f8
Merge "Removed event_id property from config"