This was mostly unused. We should simply be able to use CodeKind plus
related predicates instead.

Replace FeedbackVector::optimization_tier with
maybe_has_optimized_code, which states whether the optimized code
cache is filled. The value is updated lazily and may lag behind the
actual code cache state. We only use this field for quick cache-empty?
checks from generated code.

Bug: v8:7700,v8:12552
Change-Id: Ibfc5c0128eac56167a68ecba5690eab2e9369640
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3460741Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79107}