Remove further compat code from Tramp

Remove further compat code from Tramp

* lisp/net/tramp-adb.el (tramp-adb-handle-process-file):
Use `process-file-return-signal-string'.

* lisp/net/tramp-cache.el (tramp-dump-connection-properties):
Use "lisp-data" for persistency file.

* lisp/net/tramp-cmds.el (tramp-cleanup-this-connection)
(tramp-rename-these-files, tramp-recompile-elpa):
Declare `completion'.

* lisp/net/tramp-container.el (tramp-kubernetes--container)
(tramp-kubernetes--pod, tramp-kubernetes--namespace): Make more
robust.

* lisp/net/tramp-crypt.el (tramp-crypt-remove-directory):
Declare `completion'.

* lisp/net/tramp-gvfs.el (file-notyify-callback): Declare.

* lisp/net/tramp-sh.el (process-file-return-signal-string)
(vc-handled-backends): Don't declare.

* lisp/net/tramp-smb.el (tramp-smb-handle-copy-directory):
Use `copy-directory-create-symlink'.

* lisp/net/tramp.el (tramp-skeleton-write-region): Use `lock-file' and
`unlock-file'..
(tramp-handle-make-lock-file-name): Use `remote-file-name-inhibit-locks'.
(tramp-handle-unlock-file): Use `remote-file-name-inhibit-locks'
and `userlock--handle-unlock-error'.
(tramp-handle-shell-command): Use `shell-command-buffer-name-async'
and `shell-command-buffer-name'.
(tramp-read-passwd): Remove workaround.

(cherry picked from commit 1b806a200edcb893471237f47e969dbb9d6a99f1)