bitlbee: Delete (duplicate) OWN_DIRS for ${VARBASE}/run/bitlbee (NFCI)

${VARBASE}/run/bitlbee is already handled via OWN_DIRS_PERMS so the OWN_DIRS is
not strictly needed.

Pointed out by pkgtasks (and _USE_NEW_PKGINSTALL=yes).

(leot)