Revert "Internal: Update //buildenv/target:gce to //buildenv/target:n…

…on_prod."

This reverts commit 2e760be69dc998f7f7e20abd6b9ef172dcd72964.

Reason for revert: This change breaks the "cut release" step in our nightly validation workflow

Change-Id: I6eb9d2e346032045943be5afa23762cb1beb2900
Bug: b/378725880
GitOrigin-RevId: 323e8ff46ff3fbea4e09fded48ebb9fae454bf3d

public/BUILD

@@ -1,4 +1,3 @@
-load("//third_party/protobuf/bazel:proto_library.bzl", "proto_library")
 load("//tools/build_defs/proto/cpp:cc_proto_library.bzl", "cc_proto_library")
 
 package(