Switch to upstream 'kitchen-salt' gem for Kitchen tests

- Also fix docker/openstack ruby dependencies

Fixes: PROD-26397 (PROD:26397)

Change-Id: Ic2dab8452008758967d7869bd652ca69a3261083
diff --git a/Gemfile b/Gemfile
index 672c81e..408029d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,9 +2,12 @@
 ruby '>=2.4.0'
 gem 'rake'
 gem 'test-kitchen'
-gem 'kitchen-docker'
-gem 'kitchen-openstack'
+if File.exist?('.kitchen.openstack.yml') then
+  gem 'kitchen-openstack'
+else
+  gem 'kitchen-docker'
+end
 gem 'kitchen-inspec'
 gem 'inspec', '<3.0.0'
 #Version was frozen, because of issues in the version of inspec >3.0.0 -- see https://mirantis.jira.com/browse/PROD-24324 for more info
-gem 'kitchen-salt', :git => 'https://github.com/salt-formulas/kitchen-salt.git'
\ No newline at end of file
+gem 'kitchen-salt'