Bug 38782: Remove concat in background process

The ud_provider->{report_type} is only defined on ->harvest_sushi, meaning it'll never be defined here.
We don't need this anyway. The filename should be the filename of the file being manually uploaded. We only need this concat logic for COUNTER files being generated by Koha following a SUSHI harvest, and that works.
This also gets rid of a warning when running the tests

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit 0231911c98)
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
Signed-off-by: wainuiwitikapark <wainuiwitikapark@catalyst.net.nz>

Koha/BackgroundJob/ErmSushiHarvester.pm

@@ -92,7 +92,7 @@ sub process {
                     usage_data_provider_id => $ud_provider->erm_usage_data_provider_id,
                     file_content           => $args->{file_content},
                     date_uploaded          => POSIX::strftime( "%Y%m%d%H%M%S", localtime ),
-                    filename               => $ud_provider->name . "_" . $ud_provider->{report_type},
+                    filename               => $ud_provider->name,
                 }
             ]
         );