FIX: prevents showing discard modal on re-edit (#26639)

This commit will now change two behaviors:

- If composer is already opened on a specific post and we click on edit again for the same post, we will do nothing and not show the discard draft modal
- if composer is shrinked and we click on edit for the same currently edited post, we will just open the composer and not show the discard draft modal

spec/system/page_objects/components/composer.rb

@@ -34,6 +34,11 @@ module PageObjects
         self
       end
 
+      def minimize
+        find("#{COMPOSER_ID} .toggle-minimize").click
+        self
+      end
+
       def append_content(content)
         current_content = composer_input.value
         composer_input.set(current_content + content)