Fix SendAsync_GetWithInvalidHostHeader_ThrowsException (#72779)

Author: rzikm

src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Headers.cs

@@ -395,7 +395,7 @@ public async Task SendAsync_GetWithInvalidHostHeader_ThrowsException()
             var m = new HttpRequestMessage(HttpMethod.Get, Configuration.Http.SecureRemoteEchoServer) { Version = UseVersion };
             m.Headers.Host = "hostheaderthatdoesnotmatch";
 
-            using (HttpClient client = CreateHttpClient())
+            using (HttpClient client = CreateHttpClient(CreateHttpClientHandler(allowAllCertificates: false)))
             {
                 await Assert.ThrowsAsync<HttpRequestException>(() => client.SendAsync(TestAsync, m));
             }