Turbopack + Relay: don’t manually provide a fallback artifact_directory (#8660)
`swc_relay` implements its own logic for locating the `__generated__`
directory relative to the input file[0]
Test Plan: `TURBOPACK_BUILD=1 TURBOPACK=1 pnpm test-dev
test/integration/relay-graphql-swc-single-project/test/index.test.js`
[0]
https://github.com/swc-project/plugins/blob/8c1c1513b9d445e27d47407a9a3dea4fc53e185a/packages/relay/transform/src/lib.rs#L250-L254