Do not sync peer OSDs before listing

Sync before listing was added to wait for all PG writes possibly left in queue
from the previous master to finish before listing it

But in fact it may block the cluster when EC is used and some unstable writes
are left in the queue - they block journal flushing, rollback/stabilize is
required to unblock them, but rollback/stabilize may only happen after PG is
peered. But peering needs listings, listings are requested only after sync, and
sync itself waits for currently blocked writes waiting in the queue

src/blockstore_write.cpp

@@ -115,8 +115,8 @@ bool blockstore_impl_t::enqueue_write(blockstore_op_t *op)
     else if (!wait_del)
         printf("Write %lx:%lx v%lu offset=%u len=%u\n", op->oid.inode, op->oid.stripe, op->version, op->offset, op->len);
 #endif
-    // FIXME No strict need to add it into dirty_db here, it's just left
-    // from the previous implementation where reads waited for writes
+    // No strict need to add it into dirty_db here except maybe for listings to return
+    // correct data when there are inflight operations in the queue
     uint32_t state;
     if (is_del)
         state = BS_ST_DELETE | BS_ST_IN_FLIGHT;