Relevant js that renders the button in the first place should be around

get hasOptionalOpenFormViewColumn() {
    return this.props.editable && this.env.debug && !this.props.hasOpenFormViewButton;
}

That being said, you must be in debug mode and the form must be editable in order to see that button.

So, you could extend that js function to prevent the button from appearing.

Or, inherit and modify the template that actually checks for it and renders the button, which would be 

web.ListRenderer