Do not build new core plugins on master

The delete-project and webhooks plugins are core in master
and thus do not have to be built separately anymore.

Change-Id: I4e1debf0fc14e5e870c8c2cb262fddcbc8be9f27
diff --git a/jenkins/gerrit-bazel-plugin-webhooks.yaml b/jenkins/gerrit-bazel-plugin-webhooks.yaml
index 5a6378e..0aaa7fd 100644
--- a/jenkins/gerrit-bazel-plugin-webhooks.yaml
+++ b/jenkins/gerrit-bazel-plugin-webhooks.yaml
@@ -6,7 +6,6 @@
             - stable-2.13
       - 'plugin-{name}-bazel-{branch}':
           branch:
-            - master
             - stable-2.16
             - stable-2.15
             - stable-2.14
diff --git a/jenkins/gerrit-buck-bazel-plugin-delete-project.yaml b/jenkins/gerrit-buck-bazel-plugin-delete-project.yaml
index a4b8a0f..b5badde 100644
--- a/jenkins/gerrit-buck-bazel-plugin-delete-project.yaml
+++ b/jenkins/gerrit-buck-bazel-plugin-delete-project.yaml
@@ -9,7 +9,6 @@
             - stable-2.10
       - 'plugin-{name}-bazel-{branch}':
           branch:
-            - master
             - stable-2.16
             - stable-2.15
             - stable-2.14