release steps: do not verify CHANGELOG entries

Created by: slimsag

Our current release process https://github.com/sourcegraph/sourcegraph/issues/13374 indicates that the release captain should:

• Verify for each CHANGELOG item the following (if any item does not have these, disable it, notify the owner, and remove it from the CHANGELOG):
  • It has an owner attached to it
  • It has undergone manual QA (and the QA was done on k8s.sgdev.org or at scale if the feature requires it).
  • It is covered by the regression test suite

In practice I do not think this is something the release captain can, or actually does, well. Yes it sounds ideal that every change is verified to have an owner, has undergone QA at scale, and is covered by regression tests - but I seriously doubt the release captain is actually able to effectively do this. Do they look at every commit since the last release and message every author? I doubt it.

I propose removing this and leaving it up to individual teams and dev practices to ensure this has happened. We can update handbook docs to make it clear that we expect this to be done for all changes to a reasonable degree (but I think that is already assumed by most, and perhaps already documented.)