heal_object wrote healed shards to .rustfs/tmp/<uuid>/ and only removed that tmp
dir on the success path (the final delete_all). Three early exits after the tmp
shards were written leaked the dir:
- `erasure.heal(...)?` failing midway,
- the `disks_to_heal_count == 0` early return, and
- the `?` on the post-rename remote data-dir delete.
Add the tmp cleanup before the first two, and downgrade the remote data-dir
cleanup failure to a warning (the healed shard is already renamed into place, so
that cleanup failing must not abort the heal or leak the tmp shards).
Refs backlog#799 (B20), tracked in rustfs/backlog#863.
