Migrate to bazelmod

Remove explicit dependency on Mockito as its transitively brought in
by Gerrit.

Change-Id: I4456d980490fa0753ca46d26ae24693e78a4d5d5

BUILD

diff --git a/BUILD b/BUILD
index 3be2354..40e7083 100644
--- a/BUILD
+++ b/BUILD
@@ -1,9 +1,7 @@
-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(
@@ -19,23 +17,11 @@
     resources = glob(["src/main/resources/**/*"]),
 )
 
-junit_tests(
+gerrit_plugin_tests(
     name = "websession_flatfile_tests",
     srcs = glob(["src/test/java/**/*.java"]),
     javacopts = ["-Xep:DoNotMock:OFF"],
+    plugin = "websession-flatfile",
     resources = glob(["src/test/resources/**/*"]),
     tags = ["websession-flatfile"],
-    deps = [
-        ":websession-flatfile__plugin_test_deps",
-    ],
-)
-
-java_library(
-    name = "websession-flatfile__plugin_test_deps",
-    testonly = 1,
-    visibility = ["//visibility:public"],
-    exports = PLUGIN_DEPS + PLUGIN_TEST_DEPS + [
-        ":websession-flatfile__plugin",
-        "@mockito//jar",
-    ],
 )