clean-up "nolint" comments, remove unused ones

- fix "nolint" comments to be in the correct format (`//nolint:<linters>[,<linter>`
  no leading space, required colon (`:`) and linters.
- remove "nolint" comments for errcheck, which is disabled in our config.
- remove "nolint" comments that were no longer needed (nolintlint).
- where known, add a comment describing why a "nolint" was applied.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/cri/store/image/image.go

@@ -246,6 +246,6 @@ func (s *store) delete(id, ref string) {
 		return
 	}
 	// Remove the image if it is not referenced any more.
-	s.digestSet.Remove(digest) // nolint: errcheck
+	s.digestSet.Remove(digest)
 	delete(s.images, digest.String())
 }