Revert "Replace system_ext container with system"

This reverts commit d80efafdc0df5afae43883778202c243e21b0e45.

A system partition cannot have the aconfigs of other partitions.
Revive the system_ext container for system_ext aconfigs.

Bug: 385213580
Test: "adb shell aflags list" must not be changed.
Flag: EXEMPT refactor
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:da76a663533d3ba4455ad226454a5cb7631c6f7e)
Merged-In: I92387e6d5764c750f83bd8d266f6da969e114a72
Change-Id: I92387e6d5764c750f83bd8d266f6da969e114a72
4 files changed