Improve rules_cc copybara

* # copybara-scrub suffix now works in BUILD and bzl files
* //tools/cpp is rewritten to @bazel_build//tools/cpp **in any filetype**
* //third_party/bazel_rules/rules_cc is rewritten to // **in any filetype**

PiperOrigin-RevId: 233919400
diff --git a/tools/migration/crosstool_to_starlark_lib.go b/tools/migration/crosstool_to_starlark_lib.go
index bd373f1..965bdd8 100644
--- a/tools/migration/crosstool_to_starlark_lib.go
+++ b/tools/migration/crosstool_to_starlark_lib.go
@@ -27,7 +27,7 @@
 
 // Writes the load statement for the cc_toolchain_config_lib
 func getCcToolchainConfigHeader() string {
-	return `load("@bazel_tools//tools/cpp:cc_toolchain_config_lib.bzl",
+	return `load("//tools/cpp:cc_toolchain_config_lib.bzl",
     "action_config",
     "artifact_name_pattern",
     "env_entry",