[k8s] sonobuoy: Align all images with v0.15.1 tag

We previously bumped the sonobuoy and its required tooling (e.g.
e2e.test) to the minor version 0.15, but some binaries/images were
still pointing to 0.13/0.14 versions; let's align all of them.

Change-Id: Ic27aab02fe41d7fed06d5a45796c7bddd0db9940
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>