Defer sending in QuicConnection can't be enabled on Windows

https://github.com/envoyproxy/envoy/pull/22796 enables QuicConnection defer sending on other platforms. This is an optimization to improve CPU cost in light of UDP GSO. But this QUICHE behavior change causes test failures on Windows, i.e.

Protocols/FilterIntegrationTest.H3PostHandshakeFailoverToTcp/IPv4_Http2Downstream_Http3UpstreamNghttp2NoDeferredProcessing
.\test/integration/server.h(484): error: Value of: TestUtility::waitForCounterEq(statStore(), name, value, time_system_, timeout, dispatcher)
  Actual: false (timed out waiting for cluster.cluster_0.upstream_cx_destroy to be 2, current value 1)
Expected: true
Stack trace:
  00007FF6ACD850CC: (unknown)
  00007FF6ACD84FB6: (unknown)
  00007FF6ACD9E258: (unknown)
  00007FF6ACD9E41D: (unknown)
  00007FF6ACD9EE8D: (unknown)
... Google Test internal frames ...

[2022-08-26 22:17:36.929][4684][critical][assert] [test/integration/http_integration.cc:527] assert failure: 0. Details: Timed out waiting for new connection.

And we never verified it can also improve CPU performance on Windows, given that Windows doesn't support GSO.

We should sort out those test failures and verify the improvement on Windows platform.