Move `setmocktime` to hidden category
Move `setmocktime` to hidden category

Another testing-only potential footgun command.

(cherry picked from commit f86a24b368cf4e133add769966c7652ec3b63a75)

reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin