osbuilder: Remove debian as a rootfs

Currently we do not have debian as part of the kata CI as we
do not have a mantainer, this PR removes debian as a supported
rootfs in order to have only the distros that we are supporting
and mantainining.

Fixes #3153

Signed-off-by: Gabriela Cervantes <gabriela.cervantes.tellez@intel.com>

src/runtime/pkg/katatestutils/constraints_test.go

@@ -43,7 +43,6 @@ type testDataDistro struct {
 var distros = []string{
 	"centos",
 	"clear-linux-os",
-	"debian",
 	"fedora",
 	"opensuse",
 	"rhel",