Remove FLAG_ACTIVITY_NEW_DOCUMENT when starting the deep link

If an app starts a Settings deep link with FLAG_ACTIVITY_NEW_DOCUMENT,
FLAG_ACIVITY_NEW_TASK is auto-appended by frameworks which causes a
SecurityException on the 2-pane design because starting a new task on
the right pane is not allowed.

Deep links in the 2-pane design will clear the top activities, which has
the same UX behavior of setting FLAG_ACTIVITY_NEW_DOCUMENT, so we remove
the flag in this case.

Fix: 233917580
Test: start account page via Assistant
Change-Id: Idcbeb96e441592d48686f18f3433864f2c14832a