make: move lock and rand checks to precheck target
make: move lock and rand checks to precheck target

There's no reason to wait with running contrib/scripts/lock-check.sh and
contrib/scripts/rand-check.sh until after the build (i.e. the postcheck
target) as they are using only `grep` to check. Move them to the
precheck target so these errors are caught earlier.

Updates #11730

Signed-off-by: Tobias Klauser <9249c549618448e4c699e8032ba6c7f0d7fd4b7f@distanz.ch>

cilium/cilium,tklauser/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,cilium-team/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,tgraf/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,cilium-team/cilium