Drive-by: Remove invalid DCHECK(!is_deprecated) since we cannot
guarantee this in a concurrent setting.
Drive-by: Instead, check for deprecation during dependency validation.
Drive-by: Remove addtl. invalid or outdated DCHECKs.

Bug: v8:7790
Change-Id: Ia77a82976b987fe1eaca6178dac6c7b75fbf98fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3041666Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75957}