Fix talkback issue which focus on entire grid

When there is only one condition card, sometimes talkback will focus on
entire grid. In fact, the entire grid is a recycler view which is the
container to put all contextual cards. Mark the recycler view with no
important for accessibility to fix it.

Fixes: 128896302
Test: visual
Change-Id: I177fa014ec3208001b3a490dbdf9b6b6195985ea