Revert changes made for Http2 (#5462)

Author: neha-bhargava

src/client/Microsoft.Identity.Client/Http/HttpManager.cs

@@ -223,12 +223,6 @@ private static HttpRequestMessage CreateRequestMessage(Uri endpoint, IDictionary
 
             requestMessage.Headers.Accept.Clear();
 
-#if NET5_0_OR_GREATER
-            // On .NET 5.0 and later, HTTP2 is supported through the SDK and Entra is HTTP2 compatible
-            // Note that HttpClient.DefaultRequestVersion does not work when using HttpRequestMessage objects
-            requestMessage.Version = HttpVersion.Version20; // Default to HTTP/2
-            requestMessage.VersionPolicy = HttpVersionPolicy.RequestVersionOrLower; // Allow fallback to HTTP/1.1
-#endif
             if (headers != null)
             {
                 foreach (KeyValuePair<string, string> kvp in headers)

tests/Microsoft.Identity.Test.Common/Core/Helpers/HttpSnifferClientFactory.cs

@@ -32,21 +32,6 @@ public HttpSnifferClientFactory()
                     LastHttpContentData = req.Content.ReadAsStringAsync().GetAwaiter().GetResult();
                 }
 
-                // check the .net runtime
-                var framework = RuntimeInformation.FrameworkDescription;
-
-                // This will match ".NET 5.0", ".NET 6.0", ".NET 7.0", ".NET 8.0", etc.
-                if (framework.StartsWith(".NET ", StringComparison.OrdinalIgnoreCase))
-                {
-                    // Extract the version number
-                    var versionString = framework.Substring(5).Trim(); // e.g., "6.0.0"
-                    if (Version.TryParse(versionString, out var version) && version.Major >= 5)
-                    {
-                        Assert.AreEqual(new Version(2, 0), req.Version, $"Request version mismatch: {req.Version}. MSAL on NET 5+ expects HTTP/2.0 for all requests.");
-                        // ESTS-R endpoint does not support HTTP/2.0, so we don't assert this
-                    }
-                }
-
                 RequestsAndResponses.Add((req, res));
 
                 Trace.WriteLine($"[MSAL][HTTP Request]: {req}");

tests/Microsoft.Identity.Test.Unit/CoreTests/HttpTests/HttpManagerTests.cs

@@ -634,38 +634,5 @@ protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage reques
                 return Task.FromResult(new HttpResponseMessage(System.Net.HttpStatusCode.OK));
             }
         }
-
-#if NET
-        [TestMethod]
-        public async Task SendRequestAsync_SetsHttp2VersionAndPolicy()
-        {
-            // Arrange
-            var handler = new CapturingHandler();
-            var httpClient = new HttpClient(handler);
-            var httpClientFactory = Substitute.For<IMsalHttpClientFactory>();
-            httpClientFactory.GetHttpClient().Returns(httpClient);
-
-            var httpManager = new Client.Http.HttpManager(httpClientFactory, disableInternalRetries: true);
-
-            // Act
-            await httpManager.SendRequestAsync(
-                new Uri("https://login.microsoftonline.com/common/discovery/instance?api-version=1.1&authorization_endpoint=https://login.microsoftonline.com/common/oauth2/v2.0/authorize"),
-                null,
-                null,
-                HttpMethod.Get,
-                Substitute.For<ILoggerAdapter>(),
-                doNotThrow: true,
-                bindingCertificate: null,
-                validateServerCert: null,
-                cancellationToken: CancellationToken.None,
-                retryPolicy: Substitute.For<IRetryPolicy>()
-            ).ConfigureAwait(false);
-
-            // Assert
-            Assert.IsNotNull(handler.CapturedRequest);
-            Assert.AreEqual(HttpVersion.Version20, handler.CapturedRequest.Version);
-            Assert.AreEqual(HttpVersionPolicy.RequestVersionOrLower, handler.CapturedRequest.VersionPolicy);
-        }
-#endif
     }
 }