Add default exclude paths for multi-project config (#3693)
Add default exclude paths for multi-project config (#3693)

Summary:
This follows up on the changes I made in https://github.com/facebook/relay/pull/3688 to ensure that we properly add default excludes in multi-project mode to match the one set in single-project mode

Pull Request resolved: https://github.com/facebook/relay/pull/3693

Test Plan: `FORCE_NO_WATCHMAN=1 cargo run --bin relay -- ../../../myproject/js/relay.config.json` runs correctly without an `excludes` line in my `relay.config.json` file

Reviewed By: alunyov

Differential Revision: D33116225

Pulled By: bigfootjon

fbshipit-source-id: 2a79684e094057835f0ffcbcb2e4030870c19c89

facebook/relay,facebook/relay,facebook/relay,wincent/relay,kassens/relay,voideanvalue/relay,josephsavona/relay,xuorig/relay,xuorig/relay,wincent/relay,kassens/relay,xuorig/relay,voideanvalue/relay,kassens/relay,wincent/relay,facebook/relay,josephsavona/relay,facebook/relay,voideanvalue/relay,kassens/relay,wincent/relay,xuorig/relay,kassens/relay,josephsavona/relay,xuorig/relay,kassens/relay,wincent/relay,voideanvalue/relay,voideanvalue/relay,facebook/relay,xuorig/relay,wincent/relay,voideanvalue/relay