Alarm not cleared while deleting the bgp neighbor

EFFECT:
unconfigure bgp from odl, is not clear the raised alarm.

step to repro:-
1. configure bgp neighbor in the comcli (use unreachable ip address)
2. wait for 5 min, it will raise the alarm (BGP neighbor unreachable)
3. Unconfigure BGP neighbor
4. you can see the alarm still present