Revert "Add adb keys to debuggable AOSP builds"

This reverts commit 6d453602.

Reason for revert: Suspected to have broken build_test on master:

build/make/core/tasks/vendor_module_check.mk:108: error: Error: vendor module "adb_keys" in vendor/google/security/adb in product "aosp_lionhead" being installed to out/multiproduct-20171102103809/aosp_lionhead/target/product/lionhead/root/adb_keys which is not in the vendor tree or odm tree.

Change-Id: If7c1c9f08604b1dfc1036ea6fe3cb487fafc3cf0