Remove old removed setting

Fixes #83261

src/vs/workbench/contrib/terminal/common/terminal.ts

@@ -113,7 +113,6 @@ export interface ITerminalConfiguration {
 		windows: { [key: string]: string };
 	};
 	showExitAlert: boolean;
-	experimentalBufferImpl: 'JsArray' | 'TypedArray';
 	splitCwd: 'workspaceRoot' | 'initial' | 'inherited';
 	windowsEnableConpty: boolean;
 	experimentalRefreshOnResume: boolean;