Update getBuiltinRule (#1731)

Author: fisker

rules/utils/get-builtin-rule.js

@@ -1,13 +1,6 @@
 'use strict';
 
 function getBuiltinRule(id) {
-	// TODO: Remove this when we drop support for ESLint 7
-	const eslintVersion = require('eslint/package.json').version;
-	/* c8 ignore next 3 */
-	if (eslintVersion.startsWith('7.')) {
-		return require(`eslint/lib/rules/${id}`);
-	}
-
 	return require('eslint/use-at-your-own-risk').builtinRules.get(id);
 }