multiple start rescheduling after migration L3/DHCP agent

This workaround is safe, because starting rescheduling on alive agent do nothing

Change-Id: I5b4ea431d6907e4d57d0f753d3720a470583c77f
Closes-bug: #1371561
Merge "multiple start rescheduling after migration L3/DHCP agent" into stable/5.1