Prevent touches while stylus is hovering

While using Scribe, it is possible to get sporadic touches during
the time that the stylus is not touching the screen but hovering
it; for instance, the time between completing a word and starting
a new one, "i" dots, etc.

Bug: 353919303
Test: ABTD
Flag: EXEMPT bugfix

Change-Id: I5600e2275df27fbfebb4cad84a11861871caf80a