Add bzl files to the `for_bazel_tests` filegroup

This is in preparation for adding `load()`s for the java rules

PiperOrigin-RevId: 613198175
Change-Id: If9779ce1ef4b64c32e2c5ecc52366cded49cb619

java/BUILD

diff --git a/java/BUILD b/java/BUILD
index 3a6043b..fc77d07 100644
--- a/java/BUILD
+++ b/java/BUILD
@@ -57,6 +57,7 @@
     name = "for_bazel_tests",
     srcs = [
         "BUILD",
+        ":core_rules",
         ":java_single_jar",
     ],
     visibility = ["//visibility:public"],