Ensure the 'Add Widget' button icon is not announced

This fixes the issue that TalkBack announces twice "Add widgets"
when focus on the "+ Add widgets" button in the empty state hub.

Fixes: 378580523
Flag: EXEMPT bugfix
Test: manually with TalkBack on
Change-Id: I2969c1ea4d6ee0fdd7505ae63ecd8c7388e3a5ce
1 file changed