crimson/osd: fix PG splitting logic during map gaps

crimson/osd: fix PG splitting logic during map gaps

When the OSD advances through a range of maps (map gap), it must
ensure that every epoch transition is evaluated for potential
PG splits.

This patch updates the split check to use the current OSDMap epoch
from the PG as the baseline for each step. This guarantees that
splits are checked consecutively for every map in the sequence,
preventing intermediate splits from being missed during map gap.

Fixes: https://tracker.ceph.com/issues/74504
Signed-off-by: Aishwarya Mathuria <amathuri@redhat.com>