[fuchsia] Complete migration to zx_clock_get
[fuchsia] Complete migration to zx_clock_get

zx_clock_get and zx_clock_get_new are now the same. We can complete the
migration back to zx_clock_get.

Change-Id: I6979242eb24c5d29cff002dde7b228043c1d87f2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107305
Auto-Submit: Adam Barth <261ec7bc01029d75f3df176083f56735e31b8587@google.com>
Reviewed-by: Zach Anderson <9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com>
Commit-Queue: Zach Anderson <9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com>

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