fix(android): only apply Kotlin plugin if not using built-in

[Tommy Nguyen (tido64)]

Description

Nightly builds are failing with the following error:

An exception occurred applying plugin request [id: 'org.jetbrains.kotlin.android']
> Failed to apply plugin 'org.jetbrains.kotlin.android'.
   > Cannot add extension with name 'kotlin', as there is an extension already registered with that name.

-- https://github.com/microsoft/react-native-test-app/actions/runs/28003974492/job/82881903173

Platforms affected

• Android
• iOS
• macOS
• visionOS
• Windows

Test plan

Build will still fail but on react-native-safe-area-context instead:

cd packages/app
node --run set-react-version -- nightly
yarn
cd example
yarn android