update references

Author: WeihanLi

src/Security/Authentication/Negotiate/test/Negotiate.Test/LdapAdapterTests.cs

@@ -8,31 +8,31 @@ public class LdapAdapterTests
     [Fact]
     public void DistinguishedNameWithoutCommasSuccess()
     {
-        var parts = LdapAdapter.DistinguishedNameSeparator().Split("Testing group - City");
+        var parts = LdapAdapter.DistinguishedNameSeparatorRegex.Split("Testing group - City");
 
         Assert.Equal(new[] { "Testing group - City" }, parts);
     }
 
     [Fact]
     public void DistinguishedNameWithEscapedCommaSuccess()
     {
-        var parts = LdapAdapter.DistinguishedNameSeparator().Split(@"Testing group\,City");
+        var parts = LdapAdapter.DistinguishedNameSeparatorRegex.Split(@"Testing group\,City");
 
         Assert.Equal(new[] { @"Testing group\,City" }, parts);
     }
 
     [Fact]
     public void DistinguishedNameWithNotEscapedCommaSuccess()
     {
-        var parts = LdapAdapter.DistinguishedNameSeparator().Split("Testing group,City");
+        var parts = LdapAdapter.DistinguishedNameSeparatorRegex.Split("Testing group,City");
 
         Assert.Equal(new[] { "Testing group", "City" }, parts);
     }
 
     [Fact]
     public void DistinguishedNameWithEscapedBackslashAndNotEscapedCommaSuccess()
     {
-        var parts = LdapAdapter.DistinguishedNameSeparator().Split(@"Testing group\\,City");
+        var parts = LdapAdapter.DistinguishedNameSeparatorRegex.Split(@"Testing group\\,City");
 
         Assert.Equal(new[] { @"Testing group\\", "City" }, parts);
     }