Improve vertical scrolling for smaller screens

[fscholdei]

Proposed changes

On smaller screens, the horizontal scrollbar in the fullscreen view is only displayed when editing a file as soon as the user scrolls all the way down in the modal. Otherwise, the user can only navigate horizontally using a touchpad or keyboard. With this change, the vertical scrollbar should always be displayed.

Your checklist for this pull request

Contributor:

• PR is well described and the description can be used as a commit message on squash
• Related issues linked to PR if existing and labels set
• New code is covered with unit tests
• New/updated ui components are tested inside the storybook (module ui-components only)
• Changelog entry file created in gradle/changelog
• Feature has been tested with different permissions
• Documentation updated (only necessary for new features or changed behaviour)

Reviewer:

• The clean code principles are respected (CleanCode)
• All new code/logic is implemented on the right spot / "Should this be done here?"
• UI changes fits into the layout
• The UI views / components are responsive (mobile views)
• Correct translations are available

Checklist for branch merge request (not required for forks)

• Branch is green/blue on Jenkins
• Quality Gate passed on SonarQube