[EFM Recovery] Backward Compatibility for DKGEndState field

[jordanschalm]

Context

We are deploying EFM Recovery as a Protocol HCU, so software changes need to be backward compatible with existing state and upgrade-safe. See Upgrade Plan (Notion) for details.

This issue is for implementing backward-compatibility for the DKGEndState (old) and DKGState (new) database "columns". In the current software version, a different incompatible enum is used, so when we read the database using new software, it will behave incorrectly (see #6771 (comment)).

2 Possible approaches:

• Implement a database migration which occurs during the upgrade, in the Protocol State Machine
• Change the new enum definition to be backward compatible with the old enum (same success state, failure and in-progress states will still mean different things...)

Definition of Done

• Implement one of above approaches
• Test new software version against prior-version database state (or migration)