Removing caffe2 and third_party from our code coverage (pytorch#47310)

Summary:
Our tests do not test these folders (as they shouldn't), and their inclusion in codecov obfuscates our coverage metrics.

We ask codecov to ignore these folders when calculating our coverage.

Pull Request resolved: pytorch#47310

Reviewed By: walterddr

Differential Revision: D24711775

Pulled By: janeyx99

fbshipit-source-id: 6095bb5e8d52202c7930114d2f357163d2271022

codecov.yml

@@ -18,3 +18,6 @@ comment:
 fixes:
   - "/opt/conda/lib/python3.8/site-packages/::project/"
   - "C:/Users/circleci/project/build/win_tmp/build/::project/"
+ignore:
+  - "caffe2"
+  - "third_party"