Well, the tradition of two end-time witnesses is very late, dating to the Hellenistic era at the earliest (appearing first in the Animal Apocalypse, which dates to about 201-160 BC, where the two witnesses are Enoch and Elijah, as in later Christian tradition although in Revelation they are Moses and Elijah), as it depends on an eschatology that is itself post-exilic. I suppose one could read such symbolism into the architectural details of the Temple, but I know of no such tradition that in fact does so. Also, I don't recall these pillars specified in a special emphasized (symbolic) way in visions of the eschatological temple in Ezekiel (40:49), 4QNew Jerusalem (4Q554 I 3:22), the Temple Scroll (11QTemple 30:9, 31:9), or Revelation (where all Christians become pillars in the Temple, cf. 3:12),