Make expanded system shortcuts clickable

The textview on top was consuming the clicks, so we set it to
not be focusable (clicks are handled by the parent).

This regression was caused by a TextView bug introduced in
ag/2247666, which set clickable=true if focusable=true.

Bug: 38385679
Change-Id: I0a946073919dabcd19b47cd7df2a1fcac6946cd5