Build its-jira plugin on stable-3.4 branch

Change-Id: I5e8854743e13197da178428915c42b951e40c56c
diff --git a/jenkins/gerrit-bazel-plugin-its-jira.yaml b/jenkins/gerrit-bazel-plugin-its-jira.yaml
index c4d409f..dc1333f 100644
--- a/jenkins/gerrit-bazel-plugin-its-jira.yaml
+++ b/jenkins/gerrit-bazel-plugin-its-jira.yaml
@@ -6,6 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.4
             - stable-3.3
           targets: 'plugins/its-jira:its-jira plugins/its-jira:its_jira_tests'
       - 'plugin-its-{name}-bazel-{branch}':