Remove unused config "service_down_time" reference

service_down_time was used in service API and it's not used.
It was removed at commit I1e7e8f7519ec627b96736f74ee7123d101973544.

Change-Id: Ibf9c7082e148a3253051e5d60eacc4d891420ae7
Merge "Remove unused config "service_down_time" reference"