Bug 41123: Remove useless dbh call in Koha::Patron

Test plan:
Read the patch.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Aleisha Amohia <aleisha@catalyst.net.nz>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

Koha/Patron.pm

@@ -1308,7 +1308,6 @@ sub has_restricting_overdues {
 # Fetch first delayX value from overduerules where debarredX is set, or 0 for no delay
 sub _get_overdue_debarred_delay {
     my ( $branchcode, $categorycode ) = @_;
-    my $dbh = C4::Context->dbh();
 
     # We get default rules if there is no rule for this branch
     my $rule = Koha::OverdueRules->find(