fix: correct RuleTester typings #14222

Job	Run time
Test pnpm Type Support	14s
Verify Files	2m 38s
Test Types of eslint-config-eslint	1m 2s
Test Types of eslint	1m 5s
Test (ubuntu-latest, 24.x)	3m 22s
Test (ubuntu-latest, 25.x)	3m 7s
Test Types of @eslint/js	55s
Test (ubuntu-latest, 22.x)	3m 29s
Browser Test	2m 20s
Test (ubuntu-latest, 20.x)	3m 32s
Test (ubuntu-latest, 24.x, --experimental-transform-types)	3m 27s
Test (macOS-latest, lts/*)	3m 57s
Test (windows-latest, lts/*)	4m 51s
Test (ubuntu-latest, 20.19.0)	3m 17s
	37m 16s

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