Favor destroy_by over where.first&.destroy (#15868)

* Favor `destroy_by` over `where.first&.destroy`

We can use [ActiveRecord::Relation.destroy_by][1] instead of the method
chain.

[1]:https://api.rubyonrails.org/classes/ActiveRecord/Relation.html#method-i-destroy_by

* Restoring custom behavior

Those constants are not ActiveRecord::Base objects, so don't implement
the method.

app/controllers/profile_pins_controller.rb

@@ -18,7 +18,7 @@ class ProfilePinsController < ApplicationController
 
   def update
     # for removing pinnable
-    current_user.profile_pins.where(id: params[:id]).first&.destroy
+    current_user.profile_pins.destroy_by(id: params[:id])
     bust_user_profile
     flash[:pins_success] = "🗑 Pin removed"
     redirect_back(fallback_location: "/dashboard")