Move shared imageable specs to nested imageable specs file

In order to unify all related tests with imageable, we move shared imageable
specs and remove that file.

spec/shared/system/imageable.rb

@@ -1,32 +0,0 @@
-shared_examples "imageable" do |imageable_factory_name, imageable_path, imageable_path_arguments|
-  let!(:administrator)       { create(:user) }
-  let!(:user)                { create(:user) }
-  let!(:imageable_arguments) { {} }
-  let!(:imageable)           { create(imageable_factory_name, author: user) }
-
-  before do
-    create(:administrator, user: administrator)
-
-    imageable_path_arguments.each do |argument_name, path_to_value|
-      imageable_arguments.merge!("#{argument_name}": imageable.send(path_to_value))
-    end
-  end
-
-  context "Show" do
-    scenario "Show descriptive image when exists" do
-      image = create(:image, imageable: imageable)
-
-      visit send(imageable_path, imageable_arguments)
-
-      expect(page).to have_css("img[alt='#{image.title}'][title='#{image.title}']")
-    end
-
-    scenario "Show image title when image exists" do
-      image = create(:image, imageable: imageable)
-
-      visit send(imageable_path, imageable_arguments)
-
-      expect(page).to have_content image.title
-    end
-  end
-end

spec/system/budgets/investments_spec.rb

@@ -1105,11 +1105,6 @@ describe "Budget Investments" do
                   "budget_investment_path",
                   { budget_id: "budget_id", id: "id" }
 
-  it_behaves_like "imageable",
-                  "budget_investment",
-                  "budget_investment_path",
-                  { budget_id: "budget_id", id: "id" }
-
   it_behaves_like "mappable",
                   "budget_investment",
                   "investment",

spec/system/nested_imageable_spec.rb

@@ -170,4 +170,17 @@ describe "Nested imageable" do
       expect(page).to have_css ".image-fields", count: 1, visible: :all
     end
   end
+
+  context "Show path" do
+    let(:factory) { :budget_investment }
+    let(:path) { polymorphic_path(imageable) }
+    let!(:image) { create(:image, imageable: imageable) }
+
+    scenario "Show descriptive image and image title when an image exists" do
+      visit path
+
+      expect(page).to have_css("img[alt='#{image.title}'][title='#{image.title}']")
+      expect(page).to have_content image.title
+    end
+  end
 end

spec/system/proposals_spec.rb

@@ -1293,8 +1293,6 @@ describe "Proposals" do
 
   it_behaves_like "followable", "proposal", "proposal_path", { id: "id" }
 
-  it_behaves_like "imageable", "proposal", "proposal_path", { id: "id" }
-
   it_behaves_like "mappable",
                   "proposal",
                   "proposal",