Update price list labels, in the Cost Models wizard, to read "Filter by tag key" and "Add more tag values".

For reference, see https://docs.google.com/document/d/1EJlQNB0yw5_PbmIn8T_UWrzrTv91j2X68Y-Ysi6zjRc/edit?ts=60510621

Updated mocks: https://marvelapp.com/prototype/73ii7a7/screen/68147208