Remove flag enablePerDisplayPackageContextCacheInStatusbarNotif from DesktopExperienceFlags

The flag is already in next, we don't need to enable it based on the dev setting

Bug: 407924538
Test: None - there were no usages of it
Flag: com.android.window.flags.enable_per_display_package_context_cache_in_statusbar_notif
Change-Id: I9f691e3f10ed4c1b23c8248275df1371c98ba30b