Remove the cgroups maintainer file

We don't need this because it is covered by the libcontainer MAINTAINERS
file
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

pkg/libcontainer/cgroups/MAINTAINERS

@@ -1,3 +0,0 @@
-Michael Crosby <michael@crosbymichael.com> (@crosbymichael)
-Rohit Jnagal <jnagal@google.com> (@rjnagal)
-Victor Marmol <vmarmol@google.com> (@vmarmol)