TT#76360 Fix 445197df5: add activesubscriberpreferences to api-root.t

Otherwise on jenkins in test 'ngcp-panel-test-rest-api-docker':
> not ok 57 - check for 'activesubscriberpreferences' collection in Link
> #   Failed test 'check for 'activesubscriberpreferences' collection in Link'
> #   at ./t/api-rest/api-root.t line 176.

Change-Id: Ic694f025291490e7c0415e8210180fdd8c6cfe1b

t/api-rest/api-root.t

@@ -42,6 +42,7 @@ $ua = Test::Collection->new()->ua();
 
     my @links = $res->header('Link');
     my $rels = {
+        activesubscriberpreferences => 1,
         admincerts => 1,
         admins => 1,
         applyrewrites => 1,