The current implementation of macOS flavor support (#119564) assumes a bundle directory that differs from both the iOS implementation and the official documentation. The [documentation](https://docs.flutter.dev/deployment/flavors) instructs developers to suffix their Xcode build configurations with `-<flavor>`, but the implementation assumes a space:

https://github.com/flutter/flutter/blob/5fd9ef4240d3fc239f042f49b8eb1ad24260091f/packages/flutter_tools/lib/src/macos/application_package.dart#L174-L178

Whereas the iOS implementation, which is the reference for the docs, assumes a `-<flavor>` suffix:

https://github.com/flutter/flutter/blob/a257efc2841ed7042322fbd043f0983e705d7da2/packages/flutter_tools/lib/src/ios/xcodeproj.dart#L482-L488

This change replaces the empty space with the `-` character which is in line with the documentation and iOS implementation, as well as removing the sentence-casing applied to the flavor name; every bundle built with a flavor keeps the original flavor name in its filename.

*List which issues are fixed by this PR. You must list at least one issue.*
#122684.

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*