Remove FormulaTextAuditor.

[reitermarkus]

Verification

• This issue's title and/or description do not reference a single formula e.g. brew install wget. If they do, open an issue at https://github.com/Homebrew/homebrew-core/issues/new/choose instead.

Provide a detailed description of the proposed feature

Replace FormulaTextAuditor with RuboCops, if it isn't already.

What is the motivation for the feature?

FormulaTextAuditor is only used for two audits.

How will the feature be relevant to at least 90% of Homebrew users?

Easier maintenance.

What alternatives to the feature have been considered?

None.

[issyl0]

Yay! Were you planning on working on this, Markus, or can I take it? I have time this weekend to work on some of this (I'm on-call, so at home for once).

[issyl0]

The audit_text audit requires loading a formula and looking at its name, aliases and bin/sbin/etc. binary names. Since RuboCop is just a massive text processor, we might have to keep it around?

[reitermarkus]

We load the formula anyways for audit, so we could add a TestAuditor which audits the test block by calling the block with overridden system, shell_output and pipe_output methods and method_missing with a list of allowed test methods.