Bazel: Use test dependencies directly in junit_tests rule

Also remove local tag, because the tests can also be executed
sandboxed.

Change-Id: I38a10423b6ddf4cd297951db86a87ddc819a642f

BUILD

diff --git a/BUILD b/BUILD
index 1379fbc..f2ccbdb 100644
--- a/BUILD
+++ b/BUILD
@@ -23,21 +23,8 @@
     name = "webhooks_tests",
     srcs = glob(["src/test/java/**/*.java"]),
     resources = glob(["src/test/resources/**/*"]),
-    tags = [
-        "local",
-        "webhooks",
-    ],
-    deps = [
-        ":webhooks__plugin_test_deps",
-    ],
-)
-
-java_library(
-    name = "webhooks__plugin_test_deps",
-    testonly = 1,
-    visibility = ["//visibility:public"],
-    exports = PLUGIN_DEPS + PLUGIN_TEST_DEPS + [
+    tags = ["webhooks"],
+    deps = PLUGIN_DEPS + PLUGIN_TEST_DEPS + [
         ":webhooks__plugin",
-        "@mockito//jar",
     ],
 )