Bug fix: update is_multi_zone field in metadata for update destination request

[datoug]

We have two is_multi_zone field in destinations table, one in the destination type, another in a column in destinations. The bug is we only update the first field, which causes ListDestinations call to not return the mz destination after it's upgraded, because ListDestinations filters on the second filed.

CREATE TYPE destination (
uuid uuid,
path text,
type int,
status int,
consumed_messages_retention int,
unconsumed_messages_retention int,
owner_email text,
checksum_option int,
is_multi_zone boolean,
zone_configs list<frozen<destination_zone_config>>,
schema_version int
);

CREATE TABLE destinations (
uuid uuid PRIMARY KEY,
is_multi_zone boolean,
destination frozen,
)