test/efl: make actionslider test compatible with 1.9.99

Getting access to the underlying drag_button_base data
has changed in Elementary 1.9.99 (i.e. 1.10).

https://git.enlightenment.org/core/elementary.git/commit/?id=2a52eec7f

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>