Remove DSM JSON injection

This appears to be handled already and doing it
here just dupes the content.

And it didn't add comma's between the JSON
fields which ccause JSON deserialization errors.

Additionally, it was re-encoding the Base64 again.

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/AWS/Shared/ContextPropagation.cs

@@ -17,32 +17,13 @@ internal static class ContextPropagation
     {
         internal const string InjectionKey = "_datadog";
 
-        private static void Inject(PropagationContext context, IDictionary messageAttributes, DataStreamsManager? dataStreamsManager, IMessageHeadersHelper messageHeadersHelper, bool isLegacyHeaderNamesEnabled)
+        private static void Inject(PropagationContext context, IDictionary messageAttributes, DataStreamsManager? dataStreamsManager, IMessageHeadersHelper messageHeadersHelper)
         {
             // Consolidate headers into one JSON object with <header_name>:<value>
             var sb = Util.StringBuilderCache.Acquire();
             sb.Append('{');
             SpanContextPropagator.Instance.Inject(context, sb, default(StringBuilderCarrierSetter));
 
-            if (dataStreamsManager != null && dataStreamsManager.IsEnabled && context.SpanContext?.PathwayContext != null)
-            {
-                var encodedBytes = PathwayContextEncoder.Encode(context.SpanContext.PathwayContext.Value);
-                var base64EncodedContext = Convert.ToBase64String(encodedBytes);
-                const string ddPathwayCtxBase64 = $"\"{DataStreamsPropagationHeaders.PropagationKeyBase64}\":\"";
-                sb.Append(ddPathwayCtxBase64)
-                  .Append(base64EncodedContext)
-                  .Append('"');
-
-                if (isLegacyHeaderNamesEnabled)
-                {
-                    // Both PropagationKeyBase64 and PropagationKey use the Base64 encoded context
-                    const string ddPathwayCtx = $"\"{DataStreamsPropagationHeaders.PropagationKey}\":\"";
-                    sb.Append(ddPathwayCtx)
-                      .Append(base64EncodedContext)
-                      .Append('"');
-                }
-            }
-
             if (context.SpanContext?.PathwayContext is { } pathwayContext)
             {
                 dataStreamsManager?.InjectPathwayContext(pathwayContext, AwsMessageAttributesHeadersAdapters.GetInjectionAdapter(sb));
@@ -55,11 +36,8 @@ private static void Inject(PropagationContext context, IDictionary messageAttrib
             messageAttributes[InjectionKey] = messageHeadersHelper.CreateMessageAttributeValue(resultString);
         }
 
-        public static void InjectHeadersIntoMessage(IContainsMessageAttributes carrier, SpanContext spanContext, DataStreamsManager? dataStreamsManager, IMessageHeadersHelper messageHeadersHelper)
-            => InjectHeadersIntoMessage(carrier, spanContext, dataStreamsManager, messageHeadersHelper, Tracer.Instance.Settings.IsDataStreamsLegacyHeadersEnabled);
-
         // Internal for testing only
-        internal static void InjectHeadersIntoMessage(IContainsMessageAttributes carrier, SpanContext spanContext, DataStreamsManager? dataStreamsManager, IMessageHeadersHelper messageHeadersHelper, bool isLegacyHeaderNamesEnabled)
+        internal static void InjectHeadersIntoMessage(IContainsMessageAttributes carrier, SpanContext spanContext, DataStreamsManager? dataStreamsManager, IMessageHeadersHelper messageHeadersHelper)
         {
             // add distributed tracing headers to the message
             if (carrier.MessageAttributes == null)
@@ -104,7 +82,7 @@ internal static void InjectHeadersIntoMessage(IContainsMessageAttributes carrier
             if (carrier.MessageAttributes.Count < 10)
             {
                 var context = new PropagationContext(spanContext, Baggage.Current);
-                Inject(context, carrier.MessageAttributes, dataStreamsManager, messageHeadersHelper, isLegacyHeaderNamesEnabled);
+                Inject(context, carrier.MessageAttributes, dataStreamsManager, messageHeadersHelper);
             }
         }