follow pattern from working tests

Author: lewing

src/Hosting/Hosting/test/HostingApplicationDiagnosticsTests.cs

@@ -928,7 +928,7 @@ public void ActivityTraceParentAndTraceStateFromHeaders()
             Headers = new HeaderDictionary()
             {
                 {"traceparent", "00-0123456789abcdef0123456789abcdef-0123456789abcdef-01"},
-                {"tracestate", "TraceState=1"},
+                {"tracestate", "tracestate=1"},
                 {"baggage", "Key1=value1, Key2=value2"}
             }
         });
@@ -937,7 +937,7 @@ public void ActivityTraceParentAndTraceStateFromHeaders()
         Assert.Equal(ActivityIdFormat.W3C, Activity.Current.IdFormat);
         Assert.Equal("0123456789abcdef0123456789abcdef", Activity.Current.TraceId.ToHexString());
         Assert.Equal("0123456789abcdef", Activity.Current.ParentSpanId.ToHexString());
-        Assert.Equal("TraceState=1", Activity.Current.TraceStateString);
+        Assert.Equal("tracestate=1", Activity.Current.TraceStateString);
 
         Assert.Contains(Activity.Current.Baggage, pair => pair.Key == "Key1" && pair.Value == "value1");
         Assert.Contains(Activity.Current.Baggage, pair => pair.Key == "Key2" && pair.Value == "value2");