Revert^2 "Check and `speed` compile System UI on boot."

This reverts commit 6897ab2f.

Reason for revert: Protected the change with a system property.

We don't need an sepolicy change because we already have a rule for all
system properties under the `dalvik.vm.` namespace.

Bug: 227310505
Test: -
  1. Set `dalvik.vm.systemuicompilerfilter=speed` in the makefile of a
     particular product.
  2. Build a system image and flash to a device.
  3. Install an APEX.
  4. Reboot.
  5. See dex2oat invocation for `SystemUIGoogle.apk` with
     `--compiler-filter=speed`.
Change-Id: I7e612137a3d7678bd405a892ade959c1a96d462e