[Header] Remove birth date from header.

For privacy reasons, only name will be displayed in the actual actor selection menu in the header.

Personal number for persons the user has access to will be displayed in the actor selection list when opened, as well as the actor list on the "Din profil" pages.

Start by locating the header's actor selection component in this React component repository and inspect how the displayed actor details are assembled. Verify the behavior against the issue image and check the actor selection list and "Din profil" actor list separately. Done means the header menu shows only the name, while personal numbers remain available in the two specified lists.

Written by the indexing model from the issue text.