Fix problems in Tramp's async-shell-command

Fix problems in Tramp's async-shell-command

* lisp/net/tramp-adb.el (tramp-adb-handle-make-process):
* lisp/net/tramp-cache.el (top):
* lisp/net/tramp-sh.el (tramp-sh-handle-make-process):
Use `insert-file-contents-literally'.

* lisp/net/tramp.el (tramp-parse-file):
Use `insert-file-contents-literally'.
(tramp-handle-shell-command): Reorganize error-buffer handling.
(tramp-handle-start-file-process): Use `consp' instead of `listp'.

* test/lisp/net/tramp-tests.el (tramp-test31-interrupt-process):
Bind `delete-exited-processes'.
(tramp--test-async-shell-command): Bind `delete-exited-processes'.
Add additional `accept-process-output'.  Move cleanup of output
buffer ...
(tramp-test32-shell-command): ... here.  Test error buffer also
for `async-shell-command'.