Delayed tasks were never used, so remove support for it. The only
supported task type is therefore "normal", immediately scheduled tasks.

Bug: v8:12775
Change-Id: Ifd659deae2b98f424d889e4253f79d9b031a82d1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3849831Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82659}