locarepo: remove the `push` method (API)

All the logic of this function is in the exchange.push function for some time.
We just stop calling `localrepo.push` in `command.push` to have access to more
information. Leaving `localrepo.push` in place will let third-party extensions
wrap it but it would never be called by `hg push` making the wrapping useless.
Therefore, the method is removed so that third-party code fail noisily and
get properly upgraded.

mercurial/localrepo.py

@@ -1591,9 +1591,6 b' class localrepository(object):'
         """
         return util.hooks()
 
-    def push(self, remote, force=False, revs=None, newbranch=False):
-        return exchange.push(self, remote, force, revs, newbranch).cgresult
-
     def stream_in(self, remote, requirements):
         lock = self.lock()
         try: