Describe the bug

#5776 hid linux/flutter/ephemeral and windows/flutter/ephemeral with this regex:

	"**/flutter/ephemeral": true,

But since macos/Flutter/ephemeral has a capital F, it's not excluded as expected.

To Reproduce
Steps to reproduce the behavior:

1. Open a Flutter project in VSCode. You may need to be on a case-sensitive file system (the Linux default).
2. See that linux/flutter/ephemeral and windows/flutter/ephemeral correctly do not appear in the explorer.
3. See that macos/Flutter/ephemeral is still there, with files like Flutter-Generated.xcconfig.

Expected behavior
The macos ephemeral folder should be excluded just like the linux/windows ephemeral folders.

Screenshots

Please complete the following information:

• Operating System and version: Fedora Linux 43
• VS Code version: linux 1.103.2
• Dart extension version: 3.124.0
• Dart/Flutter SDK version: Flutter 3.38.3 with Dart 3.10.1