Bug 1703680: join group pagination error

In the screen that displays groups we can join
the functions associated with the 'join me' button
are given the correct group number (not the ones from
the first page of the pagination)

behatnotneeded

Change-Id: I1737947acd67258dd49f8c24bb69aacb5402aafc
(cherry picked from commit aa9ab0ca)