Remove Big submodule

.gitmodules

-[submodule "Assets/TestScenes/Big"]
-	path = Assets/TestScenes/Big
-	url = https://github.com/Unity-Technologies/ScriptableRenderLoopScenes
-	
 [submodule "Assets/ScriptableRenderPipeline/PostProcessing"]
 	path = Assets/ScriptableRenderPipeline/PostProcessing
 	url = https://github.com/Unity-Technologies/PostProcessing

Assets/TestScenes/Big.meta

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-guid: ca7cab07164223b41b386440cf25cdca
-folderAsset: yes
-timeCreated: 1477402341
-licenseType: Pro
-DefaultImporter:
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: