Fix tab indentation (#31798)

Code indentation was done with tabs in some places. Replaced with spaces.

packages/flutter/test/material/bottom_navigation_bar_test.dart

@@ -1436,7 +1436,7 @@ void main() {
       await expectLater(
         find.byType(BottomNavigationBar),
         matchesGoldenFile('bottom_navigation_bar.shifting_transition.2.$pump.png'),
-	      skip: !Platform.isLinux,
+        skip: !Platform.isLinux,
       );
     }
   });

packages/flutter/test/rendering/localized_fonts_test.dart

@@ -134,7 +134,7 @@ void main() {
                       mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                       children: <Widget>[
                         Text(character, style: style, locale: const Locale('ja')),
-	                Text(character, style: style, locale: const Locale('zh')),
+                        Text(character, style: style, locale: const Locale('zh')),
                       ],
                     ),
                   ),

packages/flutter_tools/test/integration/test_driver.dart

@@ -417,7 +417,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
     await _setupProcess(
       <String>[
         'run',
-	'--disable-service-auth-codes',
+        '--disable-service-auth-codes',
         '--machine',
         '-d',
         'flutter-tester',
@@ -608,7 +608,7 @@ class FlutterTestTestDriver extends FlutterTestDriver {
   }) async {
     await _setupProcess(<String>[
         'test',
-	'--disable-service-auth-codes',
+        '--disable-service-auth-codes',
         '--machine',
         '-d',
         'flutter-tester',