Merge pull request #47185 from cyx1231st/wip-seastore-backref-block-size

crimson/os/seastore/backref: decouple SegmentManagerGroup

Reviewed-by: Myoungwon Oh <myoungwon.oh@samsung.com>
Reviewed-by: Xuehan Xu <xxhdx1985126@gmail.com>

diff --cc src/crimson/os/seastore/backref/btree_backref_manager.cc
Simple merge

diff --cc src/crimson/os/seastore/backref/btree_backref_manager.h
Simple merge

diff --cc src/crimson/os/seastore/backref_manager.h
Simple merge

diff --cc src/crimson/os/seastore/cache.h
Simple merge

diff --cc src/crimson/os/seastore/transaction_manager.cc
Simple merge