Revert "Merge pull request #15550 from sgrif/sg-numeric-types"

This reverts commit be1db994, reversing
changes made to 6680ee94.

Reason: This changed a behavior where numeric attributes when receiving
blank values didn't change its value.

activerecord/lib/active_record/type/numeric.rb

@@ -5,14 +5,13 @@ def number?
         true
       end
 
-      def type_cast(value)
-        value = case value
-                when true then 1
-                when false then 0
-                when ::String then value.presence
-                else value
-                end
-        super(value)
+      def type_cast_for_write(value)
+        case value
+        when true then 1
+        when false then 0
+        when ::String then value.presence
+        else super
+        end
       end
 
       def changed?(old_value, new_value) # :nodoc: