vquic: drop support for OpenSSL-QUIC

- It is slower and uses more memory than the alternatives and is only
  experimental in curl.
- We disable a few tests for OpenSSL-QUIC because of flakiness
- It gets little attention from OpenSSL and we have no expectation of the
  major flaws getting corrected anytime soon.
- No one has spoken up for keeping it
- curl users building with vanilla OpenSSL can still use QUIC through the
  means of ngtcp2

Closes #20226

tests/http/test_05_errors.py

@@ -58,8 +58,6 @@ class TestErrors:
     # download files, check that we get CURLE_PARTIAL_FILE for all
     @pytest.mark.parametrize("proto", Env.http_mplx_protos())
     def test_05_02_partial_20(self, env: Env, httpd, nghttpx, proto):
-        if proto == 'h3' and env.curl_uses_ossl_quic():
-            pytest.skip("openssl-quic is flaky in yielding proper error codes")
         if proto == 'h3' and env.curl_uses_lib('quiche') and \
                 not env.curl_lib_version_at_least('quiche', '0.24.8'):
             pytest.skip("quiche issue #2277 not fixed")