Bug 39911: Remove redundant warn

Following the original test plan you notice, `THIS IS A TEST` is printed
twice:

* In the logs.
* In STDERR for the SIP server.

The latter is redundant, and also problematic for
`xt/author/pod_coverage.t` which fails the `no warnings` tests because
of that.

To test:
1. Run:
   $ ktd --shell
  k$ prove xt/author/pod_coverage.t
=> FAIL: Scary errors, lots of them
2. Apply this patch
3. Repeat 1
=> SUCCESS: Tests pass!
4. Follow the original bug test plan
=> SUCCESS: There's `THIS IS A TEST` in the logs, which was the author's
goal in the first place.
5. Sign off :-D
6. Visit bug 40144 :-P

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 9a4fd4facb)
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>

C4/SIP/Trapper.pm

@@ -68,7 +68,6 @@ $SIG{__DIE__} = sub {
     my $msg    = shift;
     my $logger = Koha::Logger->get( { interface => 'sip', category => 'STDERR' } );
     $logger->error($msg) if $logger;
-    warn $msg;    # die doesn't output the message, warn before dying
     die $msg;
 };