Fix NPC regression test failures.

These were genuine failures caused by ScenePresence.CompleteMovement() waiting for an UpdateAgent from NPC introduction that would never come.
Instead, we do not wait if the agent is an NPC.

OpenSim/Region/ScriptEngine/Shared/Tests/OSSL_ApiNpcTests.cs

@@ -180,6 +180,7 @@ namespace OpenSim.Region.ScriptEngine.Shared.Tests
         public void TestOsNpcLoadAppearance()
         {
             TestHelpers.InMethod();
+            //TestHelpers.EnableLogging();
 
             // Store an avatar with a different height from default in a notecard.
             UUID userId = TestHelpers.ParseTail(0x1);