[Sansan] Change to "return event"

[ushiront]

Please don't want other plugins to work, so please fix it. "return event"

• https://github.com/kintone/plugin-sdk/blob/master/examples/sansan/js/desktop_lookup.js#L273

Is "return" unnecessary?

• https://github.com/kintone/plugin-sdk/blob/master/examples/sansan/js/desktop_postRecords.js#L486