Revert "upload-pack: send non-HEAD symbolic refs"

This reverts commit 5e7dcad771cb873e278a0571b46910d7c32e2f6c; there
may be unbounded number of symbolic refs in the repository, but the
capability header line in the on-wire protocol has a rather low
length limit.
Git 1.8.4.4

Signed-off-by: Junio C Hamano <gitster@pobox.com>