rootwrap config files reference deleted quantum binaries

dhcp and l3 rootwrap filter files contain reference to the deleted
binary quantum-ns-metadata-proxy. This change removes these obsolete
filters.

Change-Id: Iad4772752d74a1c0535144b5faf9a1f8ae89f6a3
Closes-Bug: #1391256
(cherry picked from commit 226c4f6d809de3d6ed622a1f90b06e34506696d6)
Merge "rootwrap config files reference deleted quantum binaries" into stable/juno