Reuse `parsedAttributes` to remove an unnecessary parse in `findOrCreate`

`findOrCreate` uses the model's `prototype.parse` to parse attributes if the parse option is used. Instead of reusing the parsed attributes, it passes the plain ones to `build`. By passing `parsedAttributes` and merging the options with `{ parse: false }`, an extra call to `parse` can be skipped. This is particularly useful for complicated JSON parsing.

The only tests it failed were two which counted how often parse is called. After changing those tests, everything passes.