Add stable-2.14 and stable-2.15 branch to its-phabricator

Change-Id: I8642c7bece7bb7d46b17d28942021b73b9d4d05b
diff --git a/jenkins/gerrit-buck-bazel-plugin-its-phabricator.yaml b/jenkins/gerrit-buck-bazel-plugin-its-phabricator.yaml
index 230fcd0..bc2d873 100644
--- a/jenkins/gerrit-buck-bazel-plugin-its-phabricator.yaml
+++ b/jenkins/gerrit-buck-bazel-plugin-its-phabricator.yaml
@@ -5,9 +5,8 @@
           branch:
             - stable-2.13
             - stable-2.12
-      - 'plugin-its-{name}-bazel-{branch}-{gerrit-branch}':
+      - 'plugin-its-{name}-bazel-{branch}':
           branch:
             - master
-          gerrit-branch:
-            - master
+            - stable-2.15
             - stable-2.14