MODE-2394: Updates to the Vdb Sequencer in line with Teiid Schema

* Updates the Vdb sequencer's cnd model and lexicon to reflect the schema
  included in the latest version of teiid.
Is this a correction? If so, then there would never be existing nodes with this structure, so it's okay to change. If this is not a correction, then we need to be very careful about such changes that are not backward compatible.