Removed patches to lift CUPS' internal security features

Now, as we replace CUPS' privilege-drop user "lp" for the filters and
backends by the Snap's standard privilege-drop user "snap_daemon" and
also check the system for a suitable group for CUPS administration, we
do not need to lift CUPS' restrictions any more which we did to run
CUPS all-root.

So we are removing here the patches for

- allowing root as user for the filters and backends
- allowing the filter/backends group to be under the admin groups
- allowing to run the helper program cups-deviced as root

snapcraft.yaml

@@ -116,9 +116,6 @@ parts:
         set -eux
         patch -p0 < $SNAPCRAFT_STAGE/patches/cupsd-pass-on-ld-library-path.patch
         patch -p0 < $SNAPCRAFT_STAGE/patches/cupsd-pass-on-path.patch
-        patch -p0 < $SNAPCRAFT_STAGE/patches/cupsd-allow-root-as-cups-user.patch
-        patch -p0 < $SNAPCRAFT_STAGE/patches/cupsd-allow-group-and-systemgroup-be-the-same.patch
-        patch -p0 < $SNAPCRAFT_STAGE/patches/cups-deviced-allow-run-by-root.patch
         patch -p1 < $SNAPCRAFT_STAGE/patches/cups-airprint-support.patch
         patch -p1 < $SNAPCRAFT_STAGE/patches/cupsd-extra-check-for-admin-tasks-snap-cups-control.patch
         patch -p1 < $SNAPCRAFT_STAGE/patches/libcups-fix-convert-option-choice-names-in-ppd.patch