Sharesheet - Fix logic for a-z count

Prior logic only counted the number of grouped items. This could
result in the a-z list not being shown even though there were
additional targets. For instance, if 1 group had 9 targets, a-z
would've been hidden even though only 4 targets were present in the
ranked app row, resulting in 5 targets being inaccessible.

Fixes: 158017940
Test: atest ChooserActivityTest#fourOptionsStackedIntoOneTarget
Change-Id: I58e262e40f3064ce8a091e44d6b00163c8f4e4f3