Webform preview button triggers dataLayer push

Problem/Motivation

After enabling the dataLayer Webform module I can see that it is pushed when clicking on the preview button as well as submit button.
It should only happening once as it will corrupt the reports.

Steps to reproduce

Create webform with various pages.
Enable preview.
Add dataLayer Webform module to Settings > Handlers and configure.
Verify dataLayer push when clicking on Preview button in the form (GTM preview shows it clearly).

Proposed resolution

Ideally having a setting under Settings > Emails/Handlers > dataLayer Webform configuration to choose which button class will trigger the dataLayer push.

Remaining tasks

User interface changes

API changes

Data model changes