Add debian_build config setting to BUILD.tools

Make sure bazel_bootstrap_distfile_test still works after #11300

RELNOTES: None
PiperOrigin-RevId: 310524094

src/conditions/BUILD.tools

diff --git a/src/conditions/BUILD.tools b/src/conditions/BUILD.tools
index 15707d2..4d94790 100644
--- a/src/conditions/BUILD.tools
+++ b/src/conditions/BUILD.tools
@@ -87,3 +87,11 @@
     values = {"define": "EXECUTOR=remote"},
     visibility = ["//visibility:public"],
 )
+
+config_setting(
+    name = "debian_build",
+    values = {
+        "define": "distribution=debian",
+    },
+    visibility = ["//visibility:public"],
+)