OOR-CORS: Fix NetworkContextTest test

After the enterprise policy change, NetworkContextParams needs to
set enable_cors flag to enable the OOR-CORS even for testing.

Following tests failed at linux-oor-cors-rel bot.

- NetworkContextTest.HangingHeaderClientAbortDuringOnHeadersReceived
- NetworkContextTest.HangingHeaderClientAbortDuringOnBeforeSendHeaders

Bug: 1015289
Change-Id: I2c2dd3cd205e5e7b4520895bb3403a76a01750da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865926
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706799}

services/network/network_context_unittest.cc

@@ -179,6 +179,7 @@ mojom::NetworkContextParamsPtr CreateContextParams() {
   // Use a fixed proxy config, to avoid dependencies on local network
   // configuration.
   params->initial_proxy_config = net::ProxyConfigWithAnnotation::CreateDirect();
+  params->enable_cors = features::ShouldEnableOutOfBlinkCorsForTesting();
   return params;
 }