Use `folly::ext::test_find_resource` for thread-local test
Use `folly::ext::test_find_resource` for thread-local test

Summary:
buck2 won't materialize unknown deps, so switch to use the newer
C++ resources API, which should work with both v1 and v2.

Reviewed By: luciang

Differential Revision: D37199585

fbshipit-source-id: 57d770219c2fd21db450287077e54adc4081b926

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly