Update CDM binding flags

When bindImportant is false, the binding flag will be BIND_ALMOST_PERCEPTIBLE
(oom_score_adj = PERCEPTIBLE_MEDIUM_APP = 225). The target service will be treated
as important as a perceptible app (IMPORTANCE_VISIBLE = 200), and will be unbound when
the app is removed from task manager.

When bindImportant is true, the binding flag will be BIND_IMPORTANT
(oom_score_adj = PERCEPTIBLE_MEDIUM_APP = -700). The target service will
have the highest priority to avoid being killed (IMPORTANCE_FOREGROUND = 100).

One time permission's importance level to keep session alive is
IMPORTANCE_FOREGROUND_SERVICE = 125. In order to kill the one time permission session, the
service importance level should be higher than 125.

Fix: 211757348

Test: CDM tests
Change-Id: I41d72f1e6e362e987b49106e1a4169364a3392a2