Follow the convention to rename "metric_definitions" file to "metric_definition" as the same as others. Change-Id: Ia438419b4dd735c65161043af74f094d11255a2b
Follow the convention to rename "metric_definitions" file to "metric_definition" as the same as others. Change-Id: Ia438419b4dd735c65161043af74f094d11255a2b