Brings in the hierarchy-check sampling fix: the check now asks Tempo for traces
containing both parent and child rather than inspecting the three newest parent
traces, so a child conditional on a state the workload rarely reaches is found
wherever it occurred. Merged clean, no conflicts, no resolution decisions.
This unblocks ledger.acquire -> ledger.acquire.txtree on this branch, which was
skipped for exactly that sampling problem and is un-skipped in the next commit.