Disables snapshot transactions.

    If snapshots are disabled and a user starts a READ_ONLY
    transaction, the user will not receive an error message, but
    their transaction will be converted to a READ_WRITE transaction,
    but they will not be able to write.

    If you use the SNAPSHOT IS DISABLED clause to disable snapshots
    on a multifile database, writing to all snapshot files for all
    storage areas is disabled.