Refs #37095 - move test dependencies into an own group

Also drop some unused dependencies

Gemfile

@@ -1,3 +1,7 @@
 source 'https://rubygems.org'
 
 gemspec
+
+Dir[File.join(__dir__, 'gemfile.d', '*.rb')].each do |bundle|
+  eval_gemfile(bundle)
+end

gemfile.d/test.rb

@@ -0,0 +1,7 @@
+group :test do
+  gem "minitest-tags"
+  gem "vcr", "< 4.0.0"
+  gem "simplecov"
+  gem "simplecov-rcov"
+  gem 'theforeman-rubocop', '~> 0.0.6', require: false
+end

katello.gemspec

@@ -65,17 +65,4 @@ Gem::Specification.new do |gem|
   gem.add_dependency "deface", '>= 1.0.2', '< 2.0.0'
   gem.add_dependency "angular-rails-templates", "~> 1.1.0"
   gem.add_development_dependency "uglifier"
-
-  # Testing
-  gem.add_development_dependency "factory_bot_rails", "~> 4.5"
-  gem.add_development_dependency "minitest-tags"
-  gem.add_development_dependency "mocha"
-  gem.add_development_dependency "vcr", "< 4.0.0"
-  gem.add_development_dependency "webmock"
-  gem.add_development_dependency "simplecov"
-  gem.add_development_dependency "simplecov-rcov"
-  gem.add_development_dependency "robottelo_reporter"
-
-  # Rubocop
-  gem.add_development_dependency 'theforeman-rubocop', '~> 0.0.6'
 end