NotificationTest: revert overeager BigPictureStyle changes

When I fixed b/315128763 with ag/25693490, I accidentally updated two
unit test cases that weren't actually impacted by my fix.

Somehow, NotificationTest wasn't running *anywhere*, so we only noticed
this now.

Leave the two correctly updated unit test cases, but revert the two that
were updated in error.

Bug: 329402256
Test: atest NotificationTest
Flag: NA
Change-Id: I488c3753b4849a9ed19e1ee052bc1f2ae79485cf