Fix Bug#29163

Fix Bug#29163

* lisp/net/tramp.el (tramp-autoload-file-name-regexp):
Do not use "\\'" in regexp.  (Bug#29163)
(top) Do not run (tramp-register-autoload-file-name-handlers)
when loading tramp.el.

* test/lisp/net/tramp-tests.el (tramp--test-mock-p): New defun.
(tramp-test32-environment-variables-and-port-numbers)
(tramp-test41-asynchronous-requests): Use it.
(tramp-test42-auto-load): New test.
(tramp-test43-recursive-load, tramp-test44-remote-load-path)
(tramp-test45-delay-load, tramp-test46-unload): Rename.