Fix multiline comment in cc:BUILD.

Formatting inserts a line break into lines of the form "rule( # copybara-comment" and makes it unreversible.
Unused multiline string feels hacky but at least it works and should be reversible.

PiperOrigin-RevId: 1013917262
Change-Id: I674910573d4694d1a0278bd4c46c60817d5f7434

cc/BUILD

diff --git a/cc/BUILD b/cc/BUILD
index c43562a..955dc56 100644
--- a/cc/BUILD
+++ b/cc/BUILD
@@ -234,12 +234,14 @@
 
 cc_toolchain_alias(name = "current_cc_toolchain")
 
+# buildifier: disable=unused-variable
+# _unused_optional_current_cc_toolchain = """ # copybara-comment-this-out-please
 # Use alias, because it doesn't build on Bazel 6.
 alias(
-    # copybara-uncomment-this-please
-    name = "optional_current_cc_toolchain",  # copybara-uncomment-this-please
-    actual = "//cc/private/bazel7:optional_current_cc_toolchain",  # copybara-uncomment-this-please
-)  # copybara-uncomment-this-please
+    name = "optional_current_cc_toolchain",
+    actual = "//cc/private/bazel7:optional_current_cc_toolchain",
+)
+# """  # copybara-comment-this-out-please
 
 cc_libc_top_alias(name = "current_libc_top")