Make tramp-test43-asynchronous-requests working, again

Make tramp-test43-asynchronous-requests working, again

* test/lisp/net/tramp-tests.el (tramp-list-tramp-buffers):
Declare `tramp-list-tramp-buffers'.
(tramp--test-ignore-make-symbolic-link-error)
(tramp--test-ignore-add-name-to-file-error): Improve declaration.
(tramp--test-with-proper-process-name-and-buffer): New macro.
(tramp-test43-asynchronous-requests): Use the macro for timer,
process filter and process sentinel.  Comment the remote file
operation in the timer.  Remove further async events.  Accept
output from all processes.