Disable distance field generation in test project.

It's taking ~30 seconds to generate distance fields for built-in meshes
(not our tiles) during automated test runs on CI, and if this happens at
the wrong time it can cause async tests to time out and fail. E.g.:

```
[2024.09.19-13.55.42:741][157]LogMeshUtilities: Finished distance field build in 14.6s - 126x126x126 sparse distance field, 1.9Mb total, 0.1Mb always loaded, 52% occupied, 1322 triangles, EditorSkySphere
[2024.09.19-13.55.57:236][896]LogMeshUtilities: Finished distance field build in 14.3s - 126x126x126 sparse distance field, 1.9Mb total, 0.1Mb always loaded, 52% occupied, 1322 triangles, SM_SkySphere
[2024.09.19-13.55.58:335][ 28]LogMeshUtilities: Finished distance field build in 1.0s - 42x42x42 sparse distance field, 0.1Mb total, 0.0Mb always loaded, 96% occupied, 16 triangles, Cube
[2024.09.19-13.55.59:518][170]LogMeshUtilities: Finished distance field build in 1.2s - 42x42x42 sparse distance field, 0.1Mb total, 0.0Mb always loaded, 96% occupied, 320 triangles, Sphere
[2024.09.19-13.56.00:710][313]LogMeshUtilities: Finished distance field build in 1.0s - 42x42x42 sparse distance field, 0.1Mb total, 0.0Mb always loaded, 96% occupied, 170 triangles, Cylinder
[2024.09.19-13.56.05:147][845]LogAutomationController: Error: Test Completed. Result={Fail} Name={works with a single position} Path={Cesium.Unit.SampleHeightMostDetailed.Cesium World Terrain.works with a single position}
```

TestsProject/Config/DefaultEngine.ini

@@ -14,7 +14,7 @@ AppliedDefaultGraphicsPerformance=Maximum
 DefaultGraphicsRHI=DefaultGraphicsRHI_DX12
 
 [/Script/Engine.RendererSettings]
-r.GenerateMeshDistanceFields=True
+r.GenerateMeshDistanceFields=False
 r.DynamicGlobalIlluminationMethod=1
 r.ReflectionMethod=1
 r.Shadow.Virtual.Enable=1

TestsProject/TestsProject.uproject

@@ -1,6 +1,6 @@
 {
 	"FileVersion": 3,
-	"EngineAssociation": "5.0",
+	"EngineAssociation": "5.2",
 	"Category": "",
 	"Description": "",
 	"Plugins": [