Fix "one version" error

Jetty conflicts with appengine-integration-testing. Replaced one with the other.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=196126483

javatests/google/registry/server/BUILD

@@ -18,11 +18,12 @@ java_library(
     visibility = ["//visibility:public"],
     deps = [
         "//java/google/registry/util",
-        "//third_party/java/jetty/v6_1_22",
+        "@com_google_appengine_tools_sdk",
         "@com_google_auto_value",
         "@com_google_code_findbugs_jsr305",
         "@com_google_guava",
         "@javax_servlet_api",
+        "@org_mortbay_jetty",
     ],
 )