Minimize exceptions thrown from BodyKeySanitizer (#8313)

* dont attempt to parse bodys that aren't marked as json. avoid throwing so many exceptions

* cleanup usings

Author: scbedd

tools/test-proxy/Azure.Sdk.Tools.TestProxy/Sanitizers/BodyKeySanitizer.cs

@@ -2,7 +2,6 @@
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using System;
-using System.Net;
 
 namespace Azure.Sdk.Tools.TestProxy.Sanitizers
 {
@@ -44,25 +43,28 @@ public BodyKeySanitizer(string jsonPath, string value = "Sanitized", string rege
         public override string SanitizeTextBody(string contentType, string body)
         {
             bool sanitized = false;
-            JToken jsonO;
+            JToken jsonO = null;
 
-            try
+            if (contentType.ToLower().Contains("json"))
             {
-                // Prevent default behavior where JSON.NET will convert DateTimeOffset
-                // into a DateTime.
-                if (!LegacyConvertJsonDateTokens)
+                try
                 {
-                    jsonO = JsonConvert.DeserializeObject<JToken>(body, SerializerSettings);
+                    // Prevent default behavior where JSON.NET will convert DateTimeOffset
+                    // into a DateTime.
+                    if (!LegacyConvertJsonDateTokens)
+                    {
+                        jsonO = JsonConvert.DeserializeObject<JToken>(body, SerializerSettings);
+                    }
+                    else
+                    {
+                        jsonO = JToken.Parse(body);
+                    }
                 }
-                else
+                catch (JsonReaderException)
                 {
-                    jsonO = JToken.Parse(body);
+                    return body;
                 }
             }
-            catch(JsonReaderException)
-            {
-                return body;
-            }
 
             if (jsonO != null)
             {