SPEC-2903: fix the grep test method

While inspecting if application test is working with our latest
SPEC-2903 changes I see in job 8845 the following errors:
+ grep urn:AGL:widget:provided-api config.xml
+ '<feature' 'name=\"urn:AGL:widget:provided-api\">'
./common/scripts/application-lifecycle.sh: line 74: <feature: command not found

So let's change the grep method.
Furthermore, add a debug for the do_afm_util for being sure it work as
needed.

Bug-AGL: SPEC-2903
Change-Id: I5a8a6d98cd9dc6c1b2d1626fc6841eb2c2b16d53
Signed-off-by: Corentin LABBE <clabbe@baylibre.com>