Bug 13701: Remove hardcoded "two weeks" text from list share confirmation

Bug 13701: Remove hardcoded "two weeks" text from list share confirmation

Test plan:
1. Enable the OpacAllowSharingPrivateLists system preference
2. Create a private list and add items to it
3. In the OPAC click on the private list name and select 'Share list'
4. Input an email address and observe the text: "You will receive an
email notification if someone accepts your share within two weeks."
5. Apply patch
6. Restart services
7. Repeat step 3 & 4 and observe the text now displays: "You will receive
an email notification if someone accepts your share before it expires."

Sponsored-By: Catalyst IT
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>