Bug 37260: Check message broker for both 'about' and 'sysinfo' tabs

Bug 37260: Check message broker for both 'about' and 'sysinfo' tabs

Test plan:
1) Apply test patch only
2) Visit <staff_url>/cgi-bin/koha/about.pl
3) Notice it shows 'Using RabbitMQ' (it should show 'Using SQL polling')
4) Apply this patch, repeat 3)
5) Notice it now shows 'Using SQL polling'
6) Remove test patch. Notice it shows 'Using RabbitMQ' again.
7) Repeat test plan but for /cgi-bin/koha/about.pl?tab=sysinfo tab

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Emily Lamancusa <emily.lamancusa@montgomerycountymd.gov>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>