Bug 32221: Borrowers.password should no longer be an option

When creating a notice template the user has the option to add the borrower's
password to the template. This should be removed as the password should not be
an option to be added to a notice.

Test plan:
1) Navigate to Tools > Notices and slips
2) Either create a new notice or edit an existing notice
3) Observe that in the list of fields available to insert into the message body,
   there is the option for "borrowers.password"
4) Apply patch
5) Navigate to the same menu
6) Observe that the "borrowers.password" option is now no longer visible

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

tools/letter.pl

@@ -514,6 +514,7 @@ sub get_columns_for {
     my $rows = C4::Context->dbh->selectall_arrayref($sql, { Slice => {} });
     for my $row (@{$rows}) {
         next if $row->{'Field'} eq 'timestamp'; # this is really an irrelevant field and there may be other common fields that should be excluded from the list
+        next if $row->{'Field'} eq 'password'; # passwords can no longer be shown in notices so the password field should be removed as a template option
         push @fields, {
             value => $table_prefix . $row->{Field},
             text  => $table_prefix . $row->{Field},