Initializer to determine start state of the state machine which identifies the
state to initialize KCL when it is starting up. The initial state is determined based on the
customer configured
CoordinatorConfig.ClientVersionConfig and the current
MigrationState in DDB,
as follows
ClientVersionConfig | MigrationState (DDB) | initial client version
--------------------+---------------------------------+--------------------------------
COMPATIBLE_WITH_2X | Does not exist | CLIENT_VERSION_UPGRADE_FROM_2X
3X | Does not exist | CLIENT_VERSION_3X
COMPATIBLE_WITH_2X | CLIENT_VERSION_3X_WITH_ROLLBACK | CLIENT_VERSION_3X_WITH_ROLLBACK
3X | CLIENT_VERSION_3X_WITH_ROLLBACK | CLIENT_VERSION_3X
any | CLIENT_VERSION_2X | CLIENT_VERSION_2X
any | CLIENT_VERSION_UPGRADE_FROM_2X | CLIENT_VERSION_UPGRADE_FROM_2X
any | CLIENT_VERSION_3X | CLIENT_VERSION_3X