Bug 16125: Remove the flagged boolean in circ/circulation.tt

 Bug 16125: Remove the flagged boolean in circ/circulation.tt

Before 15632, flagged was passed in any cases: GetMessages returned an
arrayref, so:
  my $bor_messages_loop = GetMessages( $borrowernumber, 'B', $branch );
  if($bor_messages_loop){ $template->param(flagged => 1 ); }
set 'flagged'.

It seems that this variable is not needed as it's always set.

Test plan:
Confirm that the "Add a new message" link is always displayed (even if
no message exist).
Note that a "Attention" is displayed but should not, that already
existed before bug 15632.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>