Fix Tramp tests for MS Windows

* test/lisp/net/tramp-tests.el (tramp-test29-start-file-process)
(tramp-test30-make-process): Improve for MS-Windows.
1 job for master in 54 minutes and 52 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #5002
test-all

00:54:52