Every cleanup that runs after a publish or restore has finished deletes
garbage: the displaced .previous-* entry, a restored .displaced-* tree,
the fetch-* archives. A running Hermes process keeps the replaced
interpreter's DLLs mapped, so on Windows that delete can fail far past
the retry window and turned a completed update into "install failed:
[WinError 5]" (#124807).
One helper now owns that cleanup for all four sites. When the delete
fails it renames the tree to .reclaim-<uuid> (Windows permits renaming a
tree with mapped images): the old slot is free for the next publish of
the same entry, no restore can ever pick the half-deleted tree up, and
the next install or `hermes pm gc` deletes it once the hold is gone.
This replaces the sidecar marker for restored displacements (#128955)
and the warn-and-keep for previous entries from the salvaged commit:
a kept .previous-<entry> blocked the next publish of that entry, could
be restored half-deleted, and was unreachable by gc after a version bump.
bd75d30917