Don't trampoline to 2-pane Settings in xTS.

In automated testing, open SC activity directly and don't trampoline
into settings.  This reduces the amount of extraneuous code that is
running and reduces the likelihood of flakes caused by other product
changes.

Test: atest SafetyCenterSubpagesTest SafetyCenterStatusCardTest SafetyCenterQsActivityTest PrivacySubpageTest SafetyCenterActivityTest
Bug: 279327093
Change-Id: Iec404cca29a54751d87b83a7cbffb5de98653ae4