Bug 20298: Fix SMS characters counter when TranslateNotices is set

Bug 20298: Fix SMS characters counter when TranslateNotices is set

If you have multiple languages installed, the notices and slips page
uses the same HTML id multiple times, once for each language. This
prevents eg. the SMS character count javascript from working, because
each of the textareas has the same id.

Test plan:
Test the sms characters counter, with and without TranslateNotices
Make sure other features on this page still work correctly

QA: Make sure this change of id did not break something else.

Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>