Fix contactsmenu design

[jancborchardt]

• Set email addresses in maxcontrast color so they are not so present
• Remove the divider lines as they do not fit our style anymore and they are not needed for narrow lists like these
• Adjust the height so a half entry is cut off, so people immediately see that there are more entries in the list and it’s scrollable

Before	After

Further issues tracked there, also cc @karlitschek as discussed:

• Contacts menu has horizontal scrollbar when email addresses or names are long #33965
• Contacts menu "more actions" button changes width and is styled incorrectly #33966

[CarlSchwan]

Looks good aside from the fact that this needs to be done in the scss file

[szaimen]

please address Carl's comment