C#: Delete the mixed model generator queries and adjust the CaptureNeutralModels to use the mixed version.

Author: michaelnebel

csharp/ql/src/utils/modelgenerator/CaptureMixedNeutralModels.ql

@@ -9,5 +9,5 @@
 import internal.CaptureModels
 
 from DataFlowSummaryTargetApi api, string noflow
-where noflow = Heuristic::captureNoFlow(api)
+where noflow = captureNeutral(api)
 select noflow order by noflow