Exclude yang/md-sal related bundles when building the base distribution package

This is done only when the DOINGRELEASE flag is enabled. This is not intended to
be a standard build to be used by ODL but by a specific project outside ODL.
Fixing this for backward support only.

Change-Id: I535072731d4189271b97c90338c16da1a6591b61
Signed-off-by: Moiz Raja <moraja@cisco.com>