Bug 17925: Disable debugging in reports/bor_issues_top.pl

Bug 17925: Disable debugging in reports/bor_issues_top.pl

Remove setting $debug to 1. This prevents creation of file
tmp/bor_issues_top.debug.log.
Enable warnings pragma.
Resolve a uninitialized warning on $sep like:
Use of uninitialized value $CGI::Compile::ROOT::usr_share_koha_masterclone_reports_bor_issues_top_2epl::sep in string eq at /usr/share/koha/masterclone/reports/bor_issues_top.pl line 66.

Test plan:
Restart Plack (as you always do when testing).
Remove file /tmp/bor_issues_top.debug.log.
Open Reports/Patrons with the most checkouts.
Check if the file in /tmp has not been created again.
Check the log for warnings after you restarted Plack.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Mason James <mtj@kohaaloha.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>