Remove more unused things from CryCommon and CrySystem. (#709)

Lots of unrelated removals, I basically tried to remove everything exposed via gEnv that isn't used anymore, and following the threads found a few other things to remove also.

Code/Sandbox/Editor/MainWindow.cpp

@@ -92,7 +92,6 @@ AZ_POP_DISABLE_WARNING
 #include "ErrorReportDialog.h"
 
 #include "Dialogs/PythonScriptsDialog.h"
-#include "EngineSettingsManager.h"
 
 #include "AzAssetBrowser/AzAssetBrowserWindow.h"
 #include "AssetEditor/AssetEditorWindow.h"
@@ -1941,12 +1940,6 @@ void MainWindow::ConnectivityStateChanged(const AzToolsFramework::SourceControlS
         }
     }
 
-#if defined(CRY_ENABLE_RC_HELPER)
-    CEngineSettingsManager settingsManager;
-    settingsManager.SetModuleSpecificBoolEntry("RC_EnableSourceControl", connected);
-    settingsManager.StoreData();
-#endif
-
     gSettings.enableSourceControl = connected;
     gSettings.SaveEnableSourceControlFlag(false);
 }