Copy the final system sepolicy from oc-dev to its prebuilt dir
corresponding to its version (26.0) so that we can uprev policy and
start maintaining compatibility files, as well as use it for CTS
tests targeting future platforms.

Bug: 37896931
Test: none, this just copies the old policy.
Change-Id: Ib069d505e42595c467e5d1164fb16fcb0286ab93