Bug 20296: Untranslatable "All" in patrons table filter

Bug 20296: Untranslatable "All" in patrons table filter

There's an untranslatable "All" in the "Show X entries" filter
when browsing the patrons.

Test plan:

1) Home --> Patrons --> Browse by last name.
2) In the table filtering toolbar, there's a dropdown with
   "Show [20] entries" and the last in the dropdown is "All".
3) Update and install a language, check that msgid "All" is
   translated and isn't fuzzy.
4) Check the "All" in the dropdown, it is not translated.
5) Install patch, repeat 1-3, and check the "All" in the dropdown,
   it should now be translated.

Signed-off-by: Pasi Kallinen <pasi.kallinen@joensuu.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>