Do not cache enabled tags in Java.

As we are elimating the Binder notifications for the sysprop update for
atrace, we no longer have a callback that can be used to read the new
value of the enabled tags.

@CritivalNative calls are very fast (25 ns) so the overhead of always
going to native code to read the tags is negligible.

Test: flash & boot
Test: adb shell su root atrace -t 10 ss
Test: adb shell su root atrace -t 10 wm

Bug: 137366208
Change-Id: I1a07fefd751ee28ca9a632a3d78a2925e8827b9c