Bug 18094: Only search in searchable patron attributes if searching in standard fields

Test plan:
- Add a new patron attrbute and mark it searchable
- Populate a new patron with 'potato' in that field
- Add/edit another patron to have email potato@invalidemail.com'
- Perform a patron search with query 'potato' (in standard fields)
=> Both patrons are returned
- Perform a patron search with filters 'Email' and query 'potato'
=> Only 1 patron is returned and you are redirected to the patron detail page.

Followed test plan, works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>

Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>

C4/Utils/DataTables/Members.pm

@@ -120,7 +120,7 @@ sub search {
             push @where_args, $term;
         }
 
-        if ( C4::Context->preference('ExtendedPatronAttributes') and $searchmember ) {
+        if ( $searchfieldstype eq 'standard' and C4::Context->preference('ExtendedPatronAttributes') and $searchmember ) {
             my $matching_borrowernumbers = C4::Members::Attributes::SearchIdMatchingAttribute($searchmember);
 
             for my $borrowernumber ( @$matching_borrowernumbers ) {