Fix places that were using tracer.ServiceName when they should be using DefaultServiceName

Author: andrewlock

tracer/src/Datadog.Trace/Debugger/DebuggerManager.cs

@@ -106,7 +106,7 @@ private string GetServiceName(TracerSettings tracerSettings)
         {
             try
             {
-                return TraceUtil.NormalizeTag(tracerSettings.ServiceName ?? TracerManager.Instance.DefaultServiceName);
+                return TraceUtil.NormalizeTag(tracerSettings.MutableSettings.DefaultServiceName);
             }
             catch (Exception e)
             {

tracer/src/Datadog.Trace/LibDatadog/ServiceDiscovery/ServiceDiscoveryHelper.cs

@@ -36,7 +36,7 @@ internal static StoreMetadataResult StoreTracerMetadata(TracerSettings tracerSet
                     TracerConstants.Language,
                     TracerConstants.ThreePartVersion,
                     Environment.MachineName,
-                    tracerSettings.ServiceName,
+                    tracerSettings.MutableSettings.DefaultServiceName,
                     tracerSettings.Environment,
                     tracerSettings.ServiceVersion);
 

tracer/src/Datadog.Trace/TracerManagerFactory.cs

@@ -421,7 +421,7 @@ internal static IApi GetApi(TracerSettings settings, IDogStatsd statsd, Action<D
                         TraceVersion = TracerConstants.AssemblyVersion,
                         Env = settings.Environment,
                         Version = settings.ServiceVersion,
-                        Service = settings.ServiceName,
+                        Service = settings.MutableSettings.DefaultServiceName,
                         Hostname = HostMetadata.Instance.Hostname,
                         Language = TracerConstants.Language,
                         LanguageVersion = frameworkDescription.ProductVersion,