Drop support for deployment_data
- Portable test shell definitions should not need the LAVA install helpers and should be configured to either be specific to a particular OS variant (i.e. apt or rpm or apk) or by generic.
- deployment_data contains a lot of legacy values
- Retain support only for configuring
- Drop distro-specific package install helpers and key management helpers.
Migrated from https://projects.linaro.org/browse/LAVA-1375