[API Examples] scroll_direction.0_test.dart & growth_direction.0_test.dart (#152941)

Move `scroll_direction.0_test.dart` & `growth_direction.0_test.dart` to same directory structure as the example files.

Tests were already present, only had to move them & remove the entries from the missing tests.

Part of #130459

Author: piedcipher

dev/bots/check_code_samples.dart

@@ -323,10 +323,8 @@ final Set<String> _knownMissingTests = <String>{
   'examples/api/test/material/app_bar/sliver_app_bar.2_test.dart',
   'examples/api/test/material/app_bar/sliver_app_bar.3_test.dart',
   'examples/api/test/material/navigation_rail/navigation_rail.extended_animation.0_test.dart',
-  'examples/api/test/rendering/growth_direction/growth_direction.0_test.dart',
   'examples/api/test/rendering/sliver_grid/sliver_grid_delegate_with_fixed_cross_axis_count.0_test.dart',
   'examples/api/test/rendering/sliver_grid/sliver_grid_delegate_with_fixed_cross_axis_count.1_test.dart',
-  'examples/api/test/rendering/scroll_direction/scroll_direction.0_test.dart',
   'examples/api/test/painting/star_border/star_border.0_test.dart',
   'examples/api/test/widgets/navigator/navigator.restorable_push_and_remove_until.0_test.dart',
   'examples/api/test/widgets/navigator/navigator.restorable_push.0_test.dart',