Test assets cause Unity Editor stuck and huge gc when save asset

[chenquanjun]

When save a prefab, it will load all the ConfigGraph assets include test assets in "AssetGraph/Tests/Editor/Graphs/". It stuck editor and cause huge gc.

AssetGraph/Editor/System/Model/V2/Settings.cs

Line 31 in e70a1be

public const string GRAPH_SEARCH_CONDITION = "t:UnityEngine.AssetGraph.DataModel.Version2.ConfigGraph";

AssetGraph/Editor/System/Core/AssetGraphPostprocessor.cs

Lines 144 to 153 in e70a1be

	private void NotifyAssetPostprocessorGraphs(AssetPostprocessorContext ctx)
	{
	var guids = AssetDatabase.FindAssets(Model.Settings.GRAPH_SEARCH_CONDITION);
	var executingGraphs = new List<Model.ConfigGraph> ();
	foreach(var guid in guids) {
	string path = AssetDatabase.GUIDToAssetPath(guid);
	var graph = AssetDatabase.LoadAssetAtPath<Model.ConfigGraph>(path);
	if (graph != null && graph.UseAsAssetPostprocessor) {