luacheck: add issue for suppressed W631 warning

Closes #5464

.luacheckrc

@@ -52,6 +52,7 @@ files["test/sql-tap/**/*.lua"] = {
         -- A line consists of nothing but whitespace.
         "611",
         -- Line is too long.
+        -- https://github.com/tarantool/tarantool/issues/5181
         "631"
     }
 }