refactor: no need for a 2nd loop

Author: Yizack

lib/rules/no-duplicate-class-names.js

@@ -105,17 +105,7 @@ module.exports = {
         messageId: 'duplicateClassName',
         data: { name: duplicates.join(', ') },
         fix: (fixer) => {
-          const uniqueClasses = []
-          const seenInUnique = new Set()
-
-          for (const className of classNames) {
-            if (!seenInUnique.has(className)) {
-              uniqueClasses.push(className)
-              seenInUnique.add(className)
-            }
-          }
-
-          const unique = uniqueClasses.join(' ')
+          const unique = [...seen].join(' ')
           const sourceCode = context.getSourceCode()
           const raw = sourceCode.text.slice(
             fixTarget.range[0],