Fix rspec selector for js-description-input

Originally we meant to select all chidlren input
or textarea, but this selector was selecting
all textarea which caused issues with the ACE
replacement.

spec/features/projects/snippets/create_snippet_spec.rb

@@ -9,7 +9,7 @@ describe 'Projects > Snippets > Create Snippet', :js do
   let_it_be(:project) { create(:project, :public) }
 
   def description_field
-    find('.js-description-input input,textarea')
+    find('.js-description-input').find('input,textarea')
   end
 
   def fill_form

spec/features/snippets/spam_snippets_spec.rb

@@ -6,7 +6,7 @@ describe 'User creates snippet', :js do
   let(:user) { create(:user) }
 
   def description_field
-    find('.js-description-input input,textarea')
+    find('.js-description-input').find('input,textarea')
   end
 
   before do

spec/features/snippets/user_creates_snippet_spec.rb

@@ -14,7 +14,7 @@ describe 'User creates snippet', :js do
   end
 
   def description_field
-    find('.js-description-input input,textarea')
+    find('.js-description-input').find('input,textarea')
   end
 
   def fill_form