Suspend timers when reading Tramp process output

Suspend timers when reading Tramp process output

* lisp/net/tramp-compat.el (xdg): Require.
(tramp-compat-temporary-file-directory): Set it to
$XDG_CACHE_HOME/emacs if possible.

* lisp/net/tramp.el (tramp-debug-to-file): Fix docstring.
(tramp-wrong-passwd-regexp): Add "Authentication failed" string
(from doas).
(tramp-debug-message): Simplify backtrace check.
(with-tramp-locked-connection): Suppress timers.  (Bug#49954, Bug60534)

* test/lisp/net/tramp-tests.el (tramp-test09-insert-file-contents):
Adapt test.
(tramp-test45-asynchronous-requests): Remove :unstable tag.
Adapt test.