wip (Azure#25823)

Author: nisha-bhatia

sdk/identity/Azure.Identity/tests/IdentityRecordedTestSanitizer.cs

@@ -15,6 +15,7 @@ public class IdentityRecordedTestSanitizer : RecordedTestSanitizer
     {
         public IdentityRecordedTestSanitizer()
         {
+            SanitizedHeaders.Add("secret");
             AddJsonPathSanitizer("$..refresh_token");
             AddJsonPathSanitizer("$..access_token");
         }