Use gerrit_plugin and gerrit_plugin_tests rules from bazlets

Change-Id: I7eb02a02a295fe6c525b26800a391c39e1fc322b

BUILD

diff --git a/BUILD b/BUILD
index 06c5cb2..f340c82 100644
--- a/BUILD
+++ b/BUILD
@@ -1,38 +1,26 @@
-load("//tools/bzl:junit.bzl", "junit_tests")
 load(
-    "//tools/bzl:plugin.bzl",
-    "PLUGIN_DEPS",
-    "PLUGIN_TEST_DEPS",
+    "@com_googlesource_gerrit_bazlets//:gerrit_plugin.bzl",
     "gerrit_plugin",
+    "gerrit_plugin_tests",
 )
 
 gerrit_plugin(
     name = "avatars-external",
     srcs = glob(["src/main/java/**/*.java"]),
-    resources = glob(["src/main/resources/**/*"]),
     manifest_entries = [
         "Gerrit-PluginName: avatars-external",
         "Implementation-Title: External Avatar plugin",
         "Implementation-URL: https://gerrit-review.googlesource.com/#/admin/projects/plugins/avatars-external",
         "Gerrit-AvatarProvider: com.googlesource.gerrit.plugins.avatars.external.ExternalUrlAvatarProvider",
     ],
+    resources = glob(["src/main/resources/**/*"]),
 )
 
-junit_tests(
+gerrit_plugin_tests(
     name = "avatars-external_tests",
     srcs = glob(["src/test/java/**/*.java"]),
     tags = ["avatars-external"],
     deps = [
-        ":avatars-external__plugin_test_deps",
-    ],
-)
-
-java_library(
-    name = "avatars-external__plugin_test_deps",
-    testonly = 1,
-    visibility = ["//visibility:public"],
-    exports = PLUGIN_DEPS + PLUGIN_TEST_DEPS + [
         ":avatars-external__plugin",
-        "@mockito//jar",
     ],
 )