[Backwardport] Refactor javascript code of button split widget

[vijay-wagento]

Original Pull Request

#15351
Refactor javascript code of button split widget call js component

Description

Format the javascript code in the template file spli.phtml for button widget

Fixed Issues (if relevant)

1. Issue Number Refactor javascript code of button split widget call js component #15354

Manual testing scenarios

1. N/A

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[VladimirZaets]

Hi, @vijay-wagento, I took your PR into processing, thank you for collaboration.

[magento-engcom-team]

Hi @vijay-wagento. Thank you for your contribution.
Changes from your Pull Request will be available with the upcoming 2.1.15 release.