livecheck: Skip #preprocess_url for new strategies

[samford]

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I forgot to add the new Json, Xml, and Yaml strategies to the list of strategies where #preprocess_url should be skipped and this is causing issues for a user in their tap. This is unfortunately another bug that wasn't surfaced when I tested all the related checks in our first-party taps.

In the not-too-distant future, I plan to rework how we use #preprocess_url. It only manipulates Git URLs at this point, so it arguably makes sense to move it into the Git strategy as part of some refactoring of how certain strategy #match methods work. Long story short, once that's done we won't have to worry about special-casing strategies with regard to #preprocess_url.

[BrewTestBot]

Review period skipped due to critical label.