One more round of deprecations removal.
Removed deprecated `#original_exception` in `ActionView::Template::Er…
Removed deprecated #original_exception in ActiveJob::DeserializationE…
Removed deprecated support to passing the adapter class to .queue_ada…
Removed deprecated methods in ActiveModel::Errors
`#get`, `#set`, `=`, `add_on_empty` and `add_on_blank`.
Removed deprecated :tokenizer in the length validator
Should this and #26746 have the 5.1.0 milestone?
We don't use milestone to put PRs in a bucket, only if the PR blocks the release and it is not reviewed yet.