test images: Image Promoter fixes

Prior to the Image Centralization part 4 (https://github.com/kubernetes/kubernetes/pull/81170),
a PR merged that enables the Image Promoter to run on the k/k test images.

The Image Promoter currently only builds the Conformance-related images, but the
Image Centralization part 4 centralized some of those images into agnhost, so they
need to be removed from the conformance_images list.

Additionally, https://github.com/kubernetes/kubernetes/pull/81226 proposes mounttest-user
image to be removed, and RunAsUser to be used in tests instead.

The image used by the Image Promoter (gcr.io/k8s-testimages/gcb-docker-gcloud:v20190906-745fed4)
is based on busybox, and thus, the sed binary is actually busybox. image-util.sh calls
kube::util::ensure-gnu-sed several times, which ensures that a GNU sed binary exists
(it checks by greping GNU in its --help output). Obviously, it won't match the busybox sed
binary. But the sed usage in image-util.sh is fairly simple, and the busybox sed is sufficient.

Bumps image versions for: jessie-dnsutils, nonewprivs, resource-consumer, sample-apiserver. These
images are included in the conformance_images that are being built by the Image Promoter, so
we're bumping them just to make sure we're not breaking anything and cause all the CIs to fall.
We're going to bump the image versions used in tests in a subsequent PR. The image version was not
bumped for: agnhost, kitten, nautilus, as they were already bumped by the Image Centralization part 4
PR.

hack/lib/util.sh

@@ -698,7 +698,10 @@ function kube::util::ensure_dockerized {
 #  SED: The name of the gnu-sed binary
 #
 function kube::util::ensure-gnu-sed {
-  if LANG=C sed --help 2>&1 | grep -q GNU; then
+  # NOTE: the echo below is a workaround to ensure sed is executed before the grep.
+  # see: https://github.com/kubernetes/kubernetes/issues/87251
+  sed_help="$(LANG=C sed --help 2>&1)"
+  if echo "${sed_help}" | grep -q "GNU\|BusyBox"; then
     SED="sed"
   elif command -v gsed &>/dev/null; then
     SED="gsed"