Implement OnyxSelect list description without bottom padding

[MajaZarkova]

Description

Figma

• At the moment the component is implemented as it is designed in Figma. Meaning it has the white space (border) at the top and the bottom of the flyout.
• Info from Jannick: He would like NOT to have the white space at the bottom if a list description is provided, but he was not able to concept it that way because of Figma restrictions.
• In order to be always aligned with Figma and to avoid future questions and confusions we kept the white space for now.

This cannot be shown in Figma.

Confirmations

• I have checked that there is not already a feature request for this feature.
• I confirm that are no sensitive information included in this feature request. e.g. credentials, internal project details (for employees of the Schwarz Group) etc.

Acceptance criteria

• The OnyxSelect doesn't show a (perceived) increased bottom-padding. The label itself is the padding.