Merge pull request #43123 from liu-chunmei/lba_metrics_iter

crimson/seastore: add lba tree metrics for lba tree profiling

Reviewed-by: Samuel Just <sjust@redhat.com>
Reviewed-by: Yingxin Cheng <yingxin.cheng@intel.com>

diff --cc src/crimson/os/seastore/lba_manager/btree/btree_lba_manager.cc
Simple merge

diff --cc src/crimson/os/seastore/lba_manager/btree/btree_lba_manager.h
Simple merge