Disallow optional configuration values

[SimplyDanny]

Can be avoided now due to 0d04196.

[SwiftLintBot]

	1 Warning
⚠️	If this is a user-facing change, please include a CHANGELOG entry to credit yourself! You can find it at CHANGELOG.md.

	17 Messages
📖	Linting Aerial with this PR took 0.92s vs 0.92s on main (0% slower)
📖	Linting Alamofire with this PR took 1.27s vs 1.27s on main (0% slower)
📖	Linting Brave with this PR took 7.43s vs 7.45s on main (0% faster)
📖	Linting DuckDuckGo with this PR took 4.99s vs 5.01s on main (0% faster)
📖	Linting Firefox with this PR took 10.98s vs 11.0s on main (0% faster)
📖	Linting Kickstarter with this PR took 10.03s vs 10.04s on main (0% faster)
📖	Linting Moya with this PR took 0.52s vs 0.53s on main (1% faster)
📖	Linting NetNewsWire with this PR took 2.55s vs 2.56s on main (0% faster)
📖	Linting Nimble with this PR took 0.77s vs 0.77s on main (0% slower)
📖	Linting PocketCasts with this PR took 8.42s vs 8.71s on main (3% faster)
📖	Linting Quick with this PR took 0.44s vs 0.45s on main (2% faster)
📖	Linting Realm with this PR took 4.67s vs 4.7s on main (0% faster)
📖	Linting Sourcery with this PR took 2.34s vs 2.35s on main (0% faster)
📖	Linting Swift with this PR took 4.6s vs 4.57s on main (0% slower)
📖	Linting VLC with this PR took 1.25s vs 1.25s on main (0% slower)
📖	Linting Wire with this PR took 18.19s vs 18.11s on main (0% slower)
📖	Linting WordPress with this PR took 11.87s vs 11.76s on main (0% slower)

Here's an example of your CHANGELOG entry:

* Disallow optional configuration values.  
  [SimplyDanny](https://github.com/SimplyDanny)
  [#issue_number](https://github.com/realm/SwiftLint/issues/issue_number)

note: There are two invisible spaces after the entry's text.

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