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.
2 jobs for master in 15 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #2099
test-all

00:00:13

failed #2100
test-filenotify-gio

00:00:13

 
Name Stage Failure
failed
test-all Test There has been a runner system failure, please try again
Running with gitlab-runner 11.6.0 (f100a208)
on gitlab-runner-docker cff9d373
Using Docker executor with image debian:stretch ...
Pulling docker image debian:stretch ...
Using docker image sha256:8d31923452f8b79ae91b01568d28c90e7d667a9eaff9734c6faeb017b0efa8d0 for debian:stretch ...
ERROR: Job failed (system failure): Error response from daemon: failed to start shim: exec: "docker-containerd-shim": executable file not found in $PATH: unknown (executor_docker.go:1018:3s)
failed
test-filenotify-gio Test There has been a runner system failure, please try again
Running with gitlab-runner 11.6.0 (f100a208)
on gitlab-runner-docker cff9d373
Using Docker executor with image debian:stretch ...
Pulling docker image debian:stretch ...
Using docker image sha256:8d31923452f8b79ae91b01568d28c90e7d667a9eaff9734c6faeb017b0efa8d0 for debian:stretch ...
ERROR: Job failed (system failure): Error response from daemon: failed to start shim: exec: "docker-containerd-shim": executable file not found in $PATH: unknown (executor_docker.go:1018:3s)