pass in prefix vs value to completion extension providers so command line excludes ghost text (microsoft#236000)

fixes microsoft#235996

Author: meganrogge

src/vs/workbench/contrib/terminalContrib/suggest/browser/terminalSuggestAddon.ts

@@ -156,7 +156,7 @@ export class SuggestAddon extends Disposable implements ITerminalAddon, ISuggest
 			await this._extensionService.activateByEvent('onTerminalCompletionsRequested');
 		}
 
-		const providedCompletions = await this._terminalCompletionService.provideCompletions(this._promptInputModel.value, this._promptInputModel.cursorIndex, this._shellType, token, triggerCharacter, doNotRequestExtensionCompletions);
+		const providedCompletions = await this._terminalCompletionService.provideCompletions(this._promptInputModel.prefix, this._promptInputModel.cursorIndex, this._shellType, token, triggerCharacter, doNotRequestExtensionCompletions);
 		if (!providedCompletions?.length || token.isCancellationRequested) {
 			return;
 		}