Set slice summary text to screentitle first

To improve context on search surfaces where the
setting may be ambiguous, we set the screentitle
as the summary text as the top priority. If there is
no screentitle or the it matches the title, then we
try to use the controller summary. If the controller
summary is not valid, then we show nothing.

Bug: 79780762
Test: robotests
Change-Id: If4f7f8d4a072125604ede14e3df2afd667fa24b7