Revert "Enable verity on userdebug, and add disable-verity to adb"

Build is broken.

system/core/fs_mgr/fs_mgr_verity.c: In function 'fs_mgr_setup_verity':
system/core/fs_mgr/fs_mgr_verity.c:103:20: error: 'verity_table_signature' may be used uninitialized in this function [-Werror=maybe-uninitialized]
     if (!RSA_verify(key,
                    ^
system/core/fs_mgr/fs_mgr_verity.c:374:11: note: 'verity_table_signature' was declared here
     char *verity_table_signature;
           ^
cc1: all warnings being treated as errors
make: *** [out/target/product/minnow/obj/STATIC_LIBRARIES/libfs_mgr_intermediates/fs_mgr_verity.o] Error 1
make: *** Waiting for unfinished jobs....

This reverts commit d4cea0bc.

Change-Id: I6862cc79ef9d944a2472b6fb2e46dae514cea8ce