id_in_database do not return nil value for persisted record

This removes `|| id` which were added in rails#9963 and rails#23887 since it is no
longer necessary.

activerecord/lib/active_record/persistence.rb

@@ -569,7 +569,7 @@ def _update_record(attribute_names = self.attribute_names)
         rows_affected = 0
         @_trigger_update_callback = true
       else
-        rows_affected = self.class.unscoped._update_record attributes_values, id, id_in_database
+        rows_affected = self.class.unscoped._update_record(attributes_values, id_in_database)
         @_trigger_update_callback = rows_affected > 0
       end
 

activerecord/lib/active_record/relation.rb

@@ -67,7 +67,7 @@ def insert(values) # :nodoc:
         binds)
     end
 
-    def _update_record(values, id, id_was) # :nodoc:
+    def _update_record(values, id) # :nodoc:
       substitutes, binds = substitute_values values
 
       scope = @klass.unscoped
@@ -76,7 +76,7 @@ def _update_record(values, id, id_was) # :nodoc:
         scope.unscope!(where: @klass.inheritance_column)
       end
 
-      relation = scope.where(@klass.primary_key => (id_was || id))
+      relation = scope.where(@klass.primary_key => id)
       bvs = binds + relation.bound_attributes
       um = relation
         .arel

activerecord/lib/active_record/validations/uniqueness.rb

@@ -17,7 +17,7 @@ def validate_each(record, attribute, value)
         relation = build_relation(finder_class, attribute, value)
         if record.persisted?
           if finder_class.primary_key
-            relation = relation.where.not(finder_class.primary_key => record.id_in_database || record.id)
+            relation = relation.where.not(finder_class.primary_key => record.id_in_database)
           else
             raise UnknownPrimaryKey.new(finder_class, "Can not validate uniqueness for persisted record without primary key.")
           end