Adapt some changes of last Tramp commit

Adapt some changes of last Tramp commit

* lisp/net/tramp-container.el (tramp-container--completion-function):
Use METHOD as argument, instead of PROGRAM.  Determine program
from METHOD entry in `tramp-methods'.  Bind `non-essential' to
nil.  Use a file property as cache.
(tramp-container--completion-function): Use adapted arguments when
setting for "docker" and "podman".

* lisp/net/tramp.el (tramp--last-hop-directory): Adapt docstring.
Move down.
(tramp-set-completion-function): Revert default case to
`file-exists-p', the workaround isn't needed anymore.
(tramp-get-completion-methods): Rename argument to MULTI-HOP.
(tramp-completion-remote-containers): Add :version.
(tramp-multi-hop-p): Bind `tramp-verbose' to nil.