"pillars > merged pulls of the last 7 days count by the pillar of the issue each closes, on the board and in the map's data" passes every time on a loaded check machine #5410

Done:

• [ ] bun test --rerun-each 30 test/pillars.test.ts -t "merged pulls of the last 7 days count by the pillar" passes, and the pull names the cause it found.
• [ ] Nothing the test promises is weakened: no longer timeouts, no retries, no dropped assertion. Wait on the state the test means, never a sleep.
• [ ] If the cause is in the product, fix the product and say so.

Files: test/pillars.test.ts and the module the cause is in. Why now: it sank one of #5221's two tries (pull #5392), which never touched it. Lead: "the last 7 days" against a wall clock can fall across a day boundary under load; give the case a fixed clock.