Add Scaffold to Tooltip code samples (#69532)

packages/flutter/lib/src/material/tooltip.dart

@@ -30,7 +30,7 @@ import 'tooltip_theme.dart';
 ///
 /// {@youtube 560 315 https://www.youtube.com/watch?v=EeEfD5fI-5Q}
 ///
-/// {@tool dartpad --template=stateless_widget_material}
+/// {@tool dartpad --template=stateless_widget_scaffold_center}
 ///
 /// This example show a basic [Tooltip] which has a [Text] as child.
 /// [message] contains your label to be shown by the tooltip when
@@ -38,17 +38,15 @@ import 'tooltip_theme.dart';
 ///
 /// ```dart
 /// Widget build(BuildContext context) {
-///   return Center(
-///     child: Tooltip(
-///       message: "I am a Tooltip",
-///       child: Text("Tap this text and hold down to show a tooltip."),
-///     ),
+///   return Tooltip(
+///     message: "I am a Tooltip",
+///     child: Text("Tap this text and hold down to show a tooltip."),
 ///   );
 /// }
 /// ```
 /// {@end-tool}
 ///
-/// {@tool dartpad --template=stateless_widget_material}
+/// {@tool dartpad --template=stateless_widget_scaffold_center}
 ///
 /// This example covers most of the attributes available in Tooltip.
 /// `decoration` has been used to give a gradient and borderRadius to Tooltip.
@@ -64,23 +62,21 @@ import 'tooltip_theme.dart';
 ///
 /// ```dart
 /// Widget build(BuildContext context) {
-///   return Center(
-///     child: Tooltip(
-///       message: "I am a Tooltip",
-///       child: Text("Tap this text and hold down to show a tooltip."),
-///       decoration: BoxDecoration(
-///         borderRadius: BorderRadius.circular(25),
-///         gradient: LinearGradient(colors: [Colors.amber, Colors.red]),
-///       ),
-///       height: 50,
-///       padding: EdgeInsets.all(8.0),
-///       preferBelow: false,
-///       textStyle: TextStyle(
-///         fontSize: 24,
-///       ),
-///       showDuration: Duration(seconds: 2),
-///       waitDuration: Duration(seconds: 1),
+///   return Tooltip(
+///     message: "I am a Tooltip",
+///     child: Text("Tap this text and hold down to show a tooltip."),
+///     decoration: BoxDecoration(
+///       borderRadius: BorderRadius.circular(25),
+///       gradient: LinearGradient(colors: [Colors.amber, Colors.red]),
+///     ),
+///     height: 50,
+///     padding: EdgeInsets.all(8.0),
+///     preferBelow: false,
+///     textStyle: TextStyle(
+///       fontSize: 24,
 ///     ),
+///     showDuration: Duration(seconds: 2),
+///     waitDuration: Duration(seconds: 1),
 ///   );
 /// }
 /// ```