When path arguments are incorrect for RestController, return HTTP 404, not 400.

When RestController encounters a mismatch between function signatures and
positional URL chunks (e.g., /authors/books vs /authors/1/books), it shouldn't
raise an HTTP 400; the issue is a nonexistant URL path, not the structure of
the request/body itself.

Change-Id: I6637f88b7da4f09497f905ebafa7bf1e3788151a