verity.mk is used to set the related variable for VB 1.0 support, but we already removed VB 1.0. This change removes the unused code. We also remove and block PRODUCT_VERITY_SIGNING_KEY in this change. Bug: 241044073 Test: atest under build/make Change-Id: Ifbcde7da27a931ef3b9d746b1c5a279d88c0ec85