Improve how we handle persistent runner variables

app/models/ci/variable.rb

@@ -12,9 +12,5 @@ module Ci
     }
 
     scope :unprotected, -> { where(protected: false) }
-
-    def to_hash
-      { key: key, value: value, public: false }
-    end
   end
 end

app/models/concerns/has_variable.rb

@@ -20,12 +20,8 @@ module HasVariable
       super(new_key.to_s.strip)
     end
 
-    def to_hash
-      { key: key, value: value, public: false }
-    end
-
     def to_runner_variable
-      to_hash
+      { key: key, value: value, public: false }
     end
   end
 end

lib/gitlab/ci/variables/collection/item.rb

@@ -3,8 +3,6 @@ module Gitlab
     module Variables
       class Collection
         class Item
-          # TODO, public by default?
-          #
           def initialize(**options)
             @variable = {
               key: options.fetch(:key),
@@ -34,17 +32,11 @@ module Gitlab
           end
 
           def self.fabricate(resource)
-            # TODO, to_runner_variable by default for class < ActiveRecord::Base
-            #
             case resource
             when Hash
               self.new(resource)
-            when ::Ci::Variable
-              self.new(resource.to_hash)
-            when ::Ci::PipelineVariable
-              self.new(resource.to_hash)
-            when ::Ci::GroupVariable
-              self.new(resource.to_hash)
+            when ::HasVariable
+              self.new(resource.to_runner_variable)
             when self
               resource.dup
             else