[bazel] Delete redundant visibility (#169493)

default_visibility is already public.

utils/bazel/llvm-project-overlay/third-party/BUILD.bazel

diff --git a/utils/bazel/llvm-project-overlay/third-party/BUILD.bazel b/utils/bazel/llvm-project-overlay/third-party/BUILD.bazel
index 04cc642..b781d41 100644
--- a/utils/bazel/llvm-project-overlay/third-party/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/third-party/BUILD.bazel
@@ -51,7 +51,6 @@
         ],
         "//conditions:default": [],
     }),
-    visibility = ["//visibility:public"],
     deps = select({
         ":llvm_zlib_enabled": [
             "@llvm_zlib//:zlib-ng",