Exclude fboss-image from on-diff jobs

Summary: `fboss-image` is an individual monorepo component that is independent from our other build components. This diff prevents running unnecessary on-diff OSS tests, especially as these run in GitHub via our actions workflows when PRs are raised.

Reviewed By: kevin645

Differential Revision: D91239059

fbshipit-source-id: e5df5080e82f02057de52bfaf209d2aac0169974

Author: KevinYakar

build/fbcode_builder/manifests/fboss

@@ -54,6 +54,7 @@ fbcode/fboss = fboss
 ^fbcode/fboss/github/docs/.*
 ^fbcode/fboss/oss/.*
 ^fbcode/fboss/github/.github/.*
+^fbcode/fboss/github/fboss-image/.*
 ^fbcode/fboss/github/.pre-commit-config.yaml
 ^fbcode/fboss/github/requirements-dev.txt