Tramp: Rework handling of temporary connection properties

Tramp: Rework handling of temporary connection properties

* doc/misc/tramp.texi (Ad-hoc multi-hops): Precise use of parallel
multi-hops.

* lisp/net/tramp-cache.el:
* lisp/net/tramp.el:
* lisp/net/tramp-adb.el:
* lisp/net/tramp-androidsu.el:
* lisp/net/tramp-cmds.el:
* lisp/net/tramp-crypt.el:
* lisp/net/tramp-gvfs.el:
* lisp/net/tramp-sh.el:
* lisp/net/tramp-smb.el: Rename connection properties "process-name",
"process-buffer" and "first-password-request" to " process-name",
" process-buffer" and " first-password-request, repectively".

* lisp/net/tramp-cache.el (tramp-dump-connection-properties):
Don't dump properties starting with a space.

(cherry picked from commit 22900b5990888cb231d65755562879108c626088)