fix(config) drop no longer existing option

config.js

@@ -1395,9 +1395,6 @@ var config = {
     // Only the default ones from will be available.
     // disableAddingBackgroundImages: false,
 
-    // Disables using screensharing as virtual background.
-    // disableScreensharingVirtualBackground: false,
-
     // Sets the background transparency level. '0' is fully transparent, '1' is opaque.
     // backgroundAlpha: 1,
 

react/features/base/config/configType.ts

@@ -312,7 +312,6 @@ export interface IConfig {
     disableRemoveRaisedHandOnFocus?: boolean;
     disableResponsiveTiles?: boolean;
     disableRtx?: boolean;
-    disableScreensharingVirtualBackground?: boolean;
     disableSelfView?: boolean;
     disableSelfViewSettings?: boolean;
     disableShortcuts?: boolean;

react/features/base/config/configWhitelist.ts

@@ -116,7 +116,6 @@ export default [
     'disableRtx',
     'disableSelfView',
     'disableSelfViewSettings',
-    'disableScreensharingVirtualBackground',
     'disableShortcuts',
     'disableShowMoreStats',
     'disableRemoveRaisedHandOnFocus',