Remove `token` and `url` fields from the `web_hooks` table
Follow-up to https://gitlab.com/gitlab-org/gitlab-ce/issues/51021
In %11.4, we introduced web_hooks.encrypted_token
and web_hooks.encrypted_url
. In %11.5, we need to remove web_hooks.token
and web_hooks.url
.
Since the data is migrated in a background migration, there should be no associated data loss.