Cleanup: applyVolumesFrom

Docker-DCO-1.1-Signed-off-by: Brian Goff <cpuguy83@gmail.com> (github: cpuguy83)
Remove volumes after build

Since these volumes are both unreferencable, and should be completely
reproducible by subsequent builds, they can be safely removed.

Built on #7672
Resolves #6993 which was closed but not dealt with.

Docker-DCO-1.1-Signed-off-by: Brian Goff <cpuguy83@gmail.com> (github: cpuguy83)