Add and apply Capybara/RSpec/HaveSelector rule

This rule was added in rubocop-capybara 2.19.0. We were following it
about 85% of the time.

Now we won't have to check both have_css and have_selector when
searching the code.

spec/system/comments/topics_spec.rb

@@ -270,7 +270,7 @@ describe "Commenting topics from proposals" do
       expect(page).to have_content "It will be done next week."
     end
 
-    expect(page).not_to have_selector("#js-comment-form-comment_#{comment.id}")
+    expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
   end
 
   scenario "Reply update parent comment responses count" do
@@ -400,7 +400,7 @@ describe "Commenting topics from proposals" do
         expect(page).to have_css "img.moderator-avatar"
       end
 
-      expect(page).not_to have_selector("#js-comment-form-comment_#{comment.id}")
+      expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
     end
 
     scenario "can not comment as an administrator" do
@@ -462,7 +462,7 @@ describe "Commenting topics from proposals" do
         expect(page).to have_css "img.admin-avatar"
       end
 
-      expect(page).not_to have_selector("#js-comment-form-comment_#{comment.id}")
+      expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
     end
 
     scenario "can not comment as a moderator", :admin do
@@ -819,7 +819,7 @@ describe "Commenting topics from budget investments" do
       expect(page).to have_content "It will be done next week."
     end
 
-    expect(page).not_to have_selector("#js-comment-form-comment_#{comment.id}")
+    expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
   end
 
   scenario "Errors on reply" do
@@ -913,7 +913,7 @@ describe "Commenting topics from budget investments" do
         expect(page).to have_css "img.moderator-avatar"
       end
 
-      expect(page).not_to have_selector("#js-comment-form-comment_#{comment.id}")
+      expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
     end
 
     scenario "can not comment as an administrator" do
@@ -975,7 +975,7 @@ describe "Commenting topics from budget investments" do
         expect(page).to have_css "img.admin-avatar"
       end
 
-      expect(page).not_to have_selector("#js-comment-form-comment_#{comment.id}")
+      expect(page).not_to have_css "#js-comment-form-comment_#{comment.id}"
     end
 
     scenario "can not comment as a moderator", :admin do