Investigate some snapshots rendering

[mfranzke]

Both of the following snapshots are displayed "collapsed":

• https://github.com/db-ux-design-system/core-web/blob/main/__snapshots__/custom-select/showcase/mobile-chrome/DBCustomSelect-should-match-screenshot-1/DBCustomSelect-should-match-screenshot.png
• https://github.com/db-ux-design-system/core-web/blob/main/__snapshots__/custom-select/showcase/mobile-safari/DBCustomSelect-should-match-screenshot-1/DBCustomSelect-should-match-screenshot.png

We should investigate whether we could somehow fix or at least mitigate this.

see also #4340, might be a possible solution.