Move metricdriver to runtime directory.

Docker-DCO-1.1-Signed-off-by: Jialin Tian <himurakenshin54@gmail.com> (github: kenshin54)
Fix broken integration test.

Docker-DCO-1.1-Signed-off-by: Jialin Tian <himurakenshin54@gmail.com> (github: kenshin54)