Add pre-build step to prep vm before build

This new build step will run before any jobs run to prep the
builder.

This change should not force using of $HOME/.local/bin just yet
but preps the macros in place for us to activate it in jobs later.
The current virtualenv method should override what's done here.

Change-Id: I55947020e2f0cdbb61f9d4e7e88927d9bc304d17
Signed-off-by: Thanh Ha <thanh.ha@linuxfoundation.org>