Remove display=none from JS, already in CSS

[synox]

Expected Behaviour

Defining the style in CSS should be sufficient:
https://github.com/adobe/helix-project-boilerplate/blob/main/styles/styles.css#L63

But it also set in JS which I think is not needed:
https://github.com/adobe/helix-project-boilerplate/blob/main/scripts/lib-franklin.js#L626

Actual Behaviour

Don't set the same property multiple times.

Reproduce Scenario (including but not limited to)

Steps to Reproduce

Platform and Version

Sample Code that illustrates the problem

Logs taken while reproducing problem

[shsteimer]

@synox @davidnuescheler I think we should also remove the set to null at https://github.com/adobe/helix-project-boilerplate/blob/main/scripts/lib-franklin.js#L594