Fix BackgroundPsql's set_query_timer_restart() issue without argument.

The set_query_timer_restart() required an argument to define a value
to query_timer_restart, but none of the existing callers passes an
argument to this function.

This changes the function to set a value without an argument.

Backpatch through 16 where the background psql TAP functions were
refactored by 664d757531.

Reviewed-by: Bharath Rupireddy, Tom Lane
Discussion: https://postgr.es/m/CAD21AoA0B6VKe_5A9nZi8i5umwSN-zJJuPVNht9DaOZ9SJumMA@mail.gmail.com
Backpatch-through: 16

src/test/perl/PostgreSQL/Test/BackgroundPsql.pm

@@ -301,7 +301,7 @@ sub set_query_timer_restart
 {
 	my $self = shift;
 
-	$self->{query_timer_restart} = shift if @_;
+	$self->{query_timer_restart} = 1;
 	return $self->{query_timer_restart};
 }