[NBI] Simplify cert retrieval script

As retrieving values is now done via a generic script, let's clean a
little bit cert retrieval in order to remove unneeded part.

Issue-ID: OOM-2688
Signed-off-by: Sylvain Desbureaux <sylvain.desbureaux@orange.com>
Change-Id: Ie7f46f848bdb433023d2d8cf170f1efe7831c4f4
1 file changed