Bug 23098: Reword success message of KOC upload process

Bug 23098: Reword success message of KOC upload process

When uploading KOC files the processing of transactions needs
to happen in a separate second step. This is why the success
message "Your file was processed" was found to be misleading.

This patch changes it to the wording suggested by Benjamin
Daeuber in the original bug report. Thx!

To test:
- Create a KOC file either manually or by downloading it
  from the plugin
- Upload the KOC file into Koha using Circulation >
  Upload offline circulation file (.koc)
- Verify the new message is clear and has no typos :)

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 286f151009f778d6d4d0890b1a8bead1a6e62bde)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>