xci: Adjust build blockers and fix functest preparation

xci: Adjust build blockers and fix functest preparation

Functest preparation is moved into the deployment job to ensure
things are prepared before we are done and functest job gets
triggered. Making the preparation in functest job will cause
us to either reinitialize venv or depend on deployment job directory.
Apart from that, the env vars necessary for functest are available
within deployment job anyways so reusing that will make running
functest simpler.

See the comments in xci-daily-jobs.yaml builder macros.

Change-Id: I4c5bbe5f4b31bb620986d75ba78de6c0fe442975
Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>