[Bifrost] Maintain a lookup index in Log metadata for replicated loglets #3302

All 45 tests pass in 1m 57s

5 files - 2 5 suites - 2 1m 57s ⏱️ - 2m 35s
45 tests - 2 45 ✅ - 1 0 💤 - 1 0 ❌ ±0
114 runs - 68 114 ✅ - 65 0 💤 - 3 0 ❌ ±0

Results for commit 88dcc5c. ± Comparison against earlier commit 58afe5c.