Revert "remote-curl: fall back to basic auth if Negotiate fails"

Revert "remote-curl: fall back to basic auth if Negotiate fails"

This reverts commit 1b0d9545bb85912a16b367229d414f55d140d3be.

That commit does fix the situation it intended to (avoiding Negotiate
even when the credentials were provided in the URL), but it creates a
more serious regression: we now never hit the conditional for "we had a
username and password, tried them, but the server still gave us a 401".
That has two bad effects:

 1. we never call credential_reject(), and thus a bogus credential
    stored by a helper will live on forever

 2. we never return HTTP_NOAUTH, so the error message the user gets is
    "The requested URL returned error: 401", instead of "Authentication
    failed".

Doing this correctly seems non-trivial, as we don't know whether the
Negotiate auth was a problem. Since this is a regression in the upcoming
v2.23.0 release (for which we're in -rc0), let's revert for now and work
on a fix separately.

(Note that this isn't a pure revert; the previous commit added a test
showing the regression, so we can now flip it to expect_success).

Reported-by: Ben Humphreys <behumphreys@atlassian.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>