Move common parts of salt deployment into shared-salt.yaml

- most of common steps for bootstrapping salt moved to
  shared-salt.yaml
- default value REPOSITORY_SUITE changed to 'testing'

Change-Id: I7bd66b8e84d266ddd424b788d2a1b5ff0c6ecad4
Reviewed-on: https://review.gerrithub.io/373554
Reviewed-by: Dennis Dmitriev <dis.xcom@gmail.com>
Tested-by: Dennis Dmitriev <dis.xcom@gmail.com>
35 files changed