Closing due to insufficient support; I still think it would be valuable to implement what I described above bitcoin#22350 (comment) and that would be much less intrusive (only adds to contrib/), but that can be a new PR.
bitcoin#22350 (comment)
Or, may be even better to just document how to use logrotate, and maybe even how to make debug.log a named pipe so that some daemon can filter or process on-the-fly. All these require no changes to bitcoind.