change container of device_state_flags from system to system_ext

This commit changes the container of device_state_flags from system to
system_ext, since the flag is used in the library and binaries installed
in system_ext partition.

Bug: 328444881
Test: presubmit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:be8d6dcd04b5d29562f1006193a338d6f1059a57)
Merged-In: I586cf7e238d362175f6b90f8809f56577d6b19bb
Change-Id: I586cf7e238d362175f6b90f8809f56577d6b19bb