Remove value from ruby_version variable
Remove value from ruby_version variable

- used to fail in a "good" way when not defined
- (as used in docker package previously)

Change-Id: I07b0d0383001b74979461a17bc2df4d6c5705dec

fuel-infra/puppet-manifests,fuel-infra/puppet-manifests,fuel-infra/puppet-manifests,fuel-infra/puppet-manifests