Remove legacy store adapters & fix prune of stake pool & epoch settings #1763

All 640 tests pass in 6m 48s

    3 files ±0   16 suites ±0 6m 48s ⏱️ + 1m 36s
640 tests +6 640 ✔️ +6 0 💤 ±0 0 ❌ ±0
678 runs +6 678 ✔️ +6 0 💤 ±0 0 ❌ ±0

Results for commit ef9c487. ± Comparison against earlier commit d31de78.