h3-proxy: fixes around H3 proxy

code:
- less exception handling in existing code
- true ip happy eyeballing
- enable certificate verification
- cf-h2-proxy: abort connection when server closed connection

tests:
- remove all --insecure and --proxy-insecure args
- make session reuse test_60_12 a working one
- resolve port conflicts between h2o and nghttpx
- use proxy args better
- make test_60_06 run shorter
- kill h2o at the end of tests, normal stop takes too long

Ref: 59213f8248 #21789
Follow-up to e78b1b3ecc #21153

Closes #21798

tests/http/conftest.py

@@ -176,7 +176,7 @@ def h2o_server(env) -> Generator[Union[H2oServer, bool], None, None]:
             h2o_logs = "\n".join(h2o.dump_logs())
             pytest.skip(f"h2o server failed to start\n{h2o_logs}")
         yield h2o
-        h2o.stop()
+        h2o.kill()
     else:
         yield False
 
@@ -190,6 +190,6 @@ def h2o_proxy(env) -> Generator[Union[H2oProxy, bool], None, None]:
             h2o_logs = "\n".join(h2o.dump_logs())
             pytest.skip(f"h2o proxy failed to start\n{h2o_logs}")
         yield h2o
-        h2o.stop()
+        h2o.kill()
     else:
         yield False