mara on !2910: "rename now, we will see if we can remove it later when
some of the users have been removed or work differently."
Nothing is held. The old name described a transient the DAG declared and
kept for its whole lifetime — precisely the thing this PR replaces — so
it outlived its own meaning the moment the derivation landed. The value
is recomputed from the running set on every call.
Kept as a function rather than inlined at its single call site, per the
above: removing it is a later step that depends on its users changing,
not something this PR should force.
Rename plus its two references (the call in `reconcile_transients` and
the module doc link). No behaviour change; the doc comment records what
the old name meant so the rename doesn't erase the reason for it.
Checked with clippy (`--all-targets -D warnings`), `cargo test -p
hive-c0re -p hive-jobq` (322 + 41 passed) and `nix fmt`.