drop issue number from source comment (tracker-tag lint)

nix/modules/hive-c0re.nix

@@ -773,7 +773,8 @@ in
         # gatewayHost null-guard falls back to loopback so a domain-less
         # config doesn't break eval (it just won't work under isolation,
         # which needs a gateway anyway). Forwarded to agents by meta.rs
-        # alongside HIVE_FORGE_URL; shares the #1693 ordering caveat.
+        # alongside HIVE_FORGE_URL; shares the same env-forwarding ordering
+        # caveat (value baked at config-generation time).
         HIVE_MATRIX_URL =
           if
             config.services.hyperhive.network.enable