Revert "use mockgen"

This reverts commit b46e63b.

Author: sreya

dockerutil/dockerfake/doc.go

@@ -1,5 +1,4 @@
 // Package dockerfake contains logic for mocking out Docker-related
 // functionality.
-//
-//go:generate mockgen -destination ./mock.go -package dockerfake github.com/coder/envbox/dockerutil DockerClient
+//go:generate mockgen -destination ./mock.go -package dockerfake github.com/coder/envbox/dockerutil/dockerfake Client
 package dockerfake