FIX: show cooked bio in user profile (#27734)

When editing your bio in your user profile and then saving it, it would be removed from the profile header section.

This was broken for over 7 years since ae68795d82 was merged 😅

Context - https://meta.discourse.org/t/after-saving-changes-to-profile-expanding-full-profile-only-shows-half/314118

spec/system/user_page/user_preferences_profile_spec.rb

@@ -7,6 +7,18 @@ describe "User preferences | Profile", type: :system do
 
   before { sign_in(user) }
 
+  describe "changing bio" do
+    it "correctly updates the bio" do
+      user_preferences_profile_page.visit(user)
+
+      user_preferences_profile_page.expand_profile_details
+      user_preferences_profile_page.fill_bio(with: "I am a human.")
+      user_preferences_profile_page.save
+
+      expect(user_preferences_profile_page.cooked_bio).to have_text("I am a human.")
+    end
+  end
+
   describe "enforcing required fields" do
     before do
       UserRequiredFieldsVersion.create!