Put track of systemUiContext before WM behind flag

Put fix I705a5212c36f99b00073f2609b70673476dc50de behind flag since it
has side effect.

Bug: 384428048
Bug: 380777677
Test: atest FrameworksCoreTests:WindowTokenClientControllerTest
Flag: com.android.window.flags.track_system_ui_context_before_wms
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:6d5ab3971f2ca2026fe4e2ecca2b27394863c274)
Merged-In: Ieb32cae2aee5865bd7b573ebd0e800cc7e8b3d25
Change-Id: Ieb32cae2aee5865bd7b573ebd0e800cc7e8b3d25