Fix color token for notebook focused cell bg (fixes #101867)

Author: Miguel Solorio

extensions/theme-defaults/themes/light_defaults.json

@@ -20,7 +20,7 @@
 		"statusBarItem.remoteBackground": "#16825D",
 		"sideBarSectionHeader.background": "#0000",
 		"sideBarSectionHeader.border": "#61616130",
-		"notebook.cellFocusBackground": "#c8ddf150",
+		"notebook.focusedCellBackground": "#c8ddf150",
 		"notebook.cellBorderColor": "#dae3e9",
 		"notebook.outputContainerBackgroundColor": "#c8ddf150",
 		"notebook.focusedCellShadow": "#00315040"