quick_discouraged_focused_test misses declarations in classes that are not direct subclasses of `QuickSpec`

[macdrevx]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Describe the bug

quick_discouraged_focused_test misses focused declarations in classes that are not direct subclasses of QuickSpec.

Complete output when running SwiftLint, including the stack trace and command used

$ swiftlint lint
Linting Swift files in current working directory
Linting 'AppDelegate.swift' (1/3)
Linting 'SceneDelegate.swift' (2/3)
Linting 'FocusedDebugTests.swift' (3/3)
Done linting! Found 0 violations, 0 serious in 3 files.

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.49.1 and 0.50.0-rc.2
• Installation method used (Homebrew, CocoaPods, building from source, etc)? Homebrew
• Paste your configuration file:

opt_in_rules:
  - quick_discouraged_focused_test

• Are you using nested configurations? No
• Which Xcode version are you using (check xcodebuild -version)? Xcode 13.4.1 Build version 13F100
• Do you have a sample that shows the issue? Yes

class FocusedDebugBaseTests: QuickSpec {
}

class FocusedDebugTests: FocusedDebugBaseTests {
    override func spec() {
        super.spec()
        // This should trigger a violation, but does not.
        fdescribe("swiftlint") {
        }
    }
}