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.
P1 of the SetDisks split (tracking backlog#815, depends on P0 backlog#816).
Give the Heal operation family its own module home: relocate set_disk/heal.rs
to set_disk/ops/heal.rs and move the HealOperations storage-api contract impl
beside its inherent helpers. The contract stays implemented for SetDisks so its
associated-type bounds are unchanged (ecstore_contract_compat_test still
covers it).
Method bodies are moved unchanged. The four inherent helpers widen from
pub(super) to pub(in crate::set_disk) to preserve their exact prior visibility
from the deeper module. get_pool_and_set now reads topology through
SetDisksCtx to keep the Heal family aligned with the P0 borrow pattern; the
read is provably identical (ctx.format()/pool_index() alias the core fields).
Runtime behavior is unchanged.