Bug 14117: Silence warnings t/SearchPazPar2.t

Bug 14117: Silence warnings t/SearchPazPar2.t

The use of relative URLS (null actually), triggers warnings.
Catch them, instead of letting them loose.

TEST PLAN
---------
1) $ prove t/Search_PazPar2.t
   -- noise for each test currently.
2) apply patch
3) $ prove t/Search_PazPar2.t
   -- No noise, and extra tests added.
      -v shows caught warning tests.
4) koha qa test tools.

Signed-off-by: Indranil Das Gupta <indradg@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>