Fix HasBetterKotlinAlternativeMethod: Use Kotlin joinToString in TextAttributeProps (#55505)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/55505

Replace `TextUtils.join(", ", features)` with Kotlin's idiomatic `features.joinToString(", ")` to fix the HasBetterKotlinAlternativeMethod lint warning. Also removed the now-unused `TextUtils` import while keeping the `TextUtils.TruncateAt` import that is still in use.

changelog: [internal] internal

Reviewed By: alanleedev

Differential Revision: D92021465

fbshipit-source-id: 3cb9e286f9f46f82817b0257dde73230ba2298d6