Fix SSPI ComputeIntegrityCheck with Sign level

Fix calling NegotiateAuthentication.ComputeIntegrityCheck on SSPI when
the negotiation context was built with ProtectionLevel.Sign. The
SECQOP_WRAP_NO_ENCRYPT QoP flag should not be set when calling GetMIC as
no encryption is involved and some authentication providers fail when
this is set.

Fix dotnet#103461

src/libraries/System.Net.Security/src/System/Net/NegotiateAuthenticationPal.Windows.cs

@@ -587,8 +587,7 @@ public override unsafe void GetMIC(ReadOnlySpan<byte> message, IBufferWriter<byt
                             pBuffers = unmanagedBuffer
                         };
 
-                        uint qop = IsEncrypted ? 0 : Interop.SspiCli.SECQOP_WRAP_NO_ENCRYPT;
-                        int errorCode = Interop.SspiCli.MakeSignature(ref _securityContext._handle, qop, ref sdcInOut, 0);
+                        int errorCode = Interop.SspiCli.MakeSignature(ref _securityContext._handle, 0, ref sdcInOut, 0);
 
                         if (errorCode != 0)
                         {