Remove unused zlib patch (#6137)

Leftover from #6063

Should have been removed along with
114ba4ecfb

changelog_begin
changelog_end

bazel_tools/proto-zlib-url.patch

@@ -1,28 +0,0 @@
-From 516f8b15603b7f7613e2fb957c55bc56a36b64a6 Mon Sep 17 00:00:00 2001
-From: Keith Smiley <keithbsmiley@gmail.com>
-Date: Wed, 28 Aug 2019 21:41:02 -0700
-Subject: [PATCH] bazel: Change zlib URL to GitHub
-
-We've notice significant issues downloading from zlib.net. Since there
-are already other archives coming from GitHub, this shouldn't negatively
-affect reliability.
----
- protobuf_deps.bzl | 4 ++--
- 1 file changed, 2 insertions(+), 2 deletions(-)
-
-diff --git a/protobuf_deps.bzl b/protobuf_deps.bzl
-index e5117d167d..9209b1c5a3 100644
---- a/protobuf_deps.bzl
-+++ b/protobuf_deps.bzl
-@@ -17,7 +17,7 @@ def protobuf_deps():
-         http_archive(
-             name = "zlib",
-             build_file = "@com_google_protobuf//:third_party/zlib.BUILD",
--            sha256 = "c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1",
-+            sha256 = "629380c90a77b964d896ed37163f5c3a34f6e6d897311f1df2a7016355c45eff",
-             strip_prefix = "zlib-1.2.11",
--            urls = ["https://zlib.net/zlib-1.2.11.tar.gz"],
-+            urls = ["https://github.com/madler/zlib/archive/v1.2.11.tar.gz"],
-         )
-
-     if not native.existing_rule("six"):