Revert "Unset PRODUCT_INSTALL_DEBUG_POLICY_TO_SYSTEM_EXT for gsi_car_${arch}.mk"
This reverts commit 9404c159499521c19ab29018da59cae12a4d92f3.
Reason for revert: b:213963330
Bug: 213963330
Test: build gsi_car_arm64
Change-Id: Ia8d34fa9b6b92052416239934480ef021d906401