sshserver: drop ancient do_{lock,unlock,addchangegroup} methods These were marked as deprecated and dangerous way back in e8c4f3d3df8c, which was first included in Mercurial 0.9.1. While it's possible that clients from that long ago are still around somewhere, they're risky for servers in that they want to lock the repo, and then might leave it locked if they died before finishing their transaction. Given that it's been 9 years, let's go ahead and cut this last lingering tie with a basically-untested protocol.