Do not set DisableByDefault

You introduced this setting [here](https://github.com/airbnb/ruby/commit/58a7e199c09bb0a913a0846e32edc8580fb956dc) but it breaks a lot of things, now even a malformed Ruby file (e.g. missing an `end`) passes as though it had no issue.

(Sorry for the terse issue, if you can't reproduce I will try to add more details later.)

Start with the linked commit that introduced DisableByDefault and reproduce the report using a malformed Ruby file, such as one missing an end. Confirm that the configuration no longer causes malformed files to pass as valid, then run the repository's available checks to verify the change.

Written by the indexing model from the issue text.