[fuchsia] swap out deprecated flag name
[fuchsia] swap out deprecated flag name

FDIO_SPAWN_CLONE_LDSVC was replaced with FDIO_SPAWN_DEFAULT_LDSVC, as it no
longer always means clone.

Fuchsia Bug: ZX-3031

Change-Id: I62ace1e8b9f87440adf7aea31424137a47d16303
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/105400
Reviewed-by: Zach Anderson <9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com>
Commit-Queue: Zach Anderson <9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com>
Auto-Submit: James Tucker <8ac5174bb962a31bfc33bc5b392acc5b9a1e9290@google.com>

dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk