Migrate pkg_tar from internal copy to @rules_pkg: Bazel packaging and
distribution.

This is one of several changes to complete this migration.

- Rules used to package and distribute Bazel. (This CL)
- third_party/...
- Rules which interact with other built-in rules.
  tools/android/runtime_deps
  src/main/cpp/util
- src/test/shell/bazel/bazel_embedded_skylark_test.sh
- Repository rule testing
  src/test/java/com/google/devtools/build/lib/blackbox/tests/workspace/...
  Defer until the incompatible flag flip.

RELNOTES: pkg_deb, pkg_rpm & pkg_tar deprecation plan announced in the documentation.
PiperOrigin-RevId: 259615722
diff --git a/BUILD b/BUILD
index 1b0bfdb..ebbdc77 100644
--- a/BUILD
+++ b/BUILD
@@ -66,7 +66,7 @@
     visibility = ["//:__subpackages__"],
 )
 
-load("//tools/build_defs/pkg:pkg.bzl", "pkg_tar")
+load("@rules_pkg//:pkg.bzl", "pkg_tar")
 
 pkg_tar(
     name = "bazel-srcs",