Add policy for add-release-to-cloudfoundry (#9364)

Author: sarahchen6

.github/chainguard/self.add-release-to-cloudfoundry.sts.yaml

@@ -0,0 +1,12 @@
+issuer: https://token.actions.githubusercontent.com
+
+subject: repo:DataDog/dd-trace-java:ref:refs/heads/master
+
+claim_pattern:
+  event_name: release
+  ref: refs/heads/master
+  ref_protected: "true"
+  job_workflow_ref: DataDog/dd-trace-java/\.github/workflows/add-release-to-cloudfoundry\.yaml@refs/heads/master
+
+permissions:
+  contents: write