Merge pull request #61418 from cbodley/wip-rgw-multisite-sync-delta-counters

rgw: add labeled counters for sync deltas of shards

Reviewed-by: Adam Emerson <aemerson@redhat.com>

diff --cc src/common/perf_counters.cc
Simple merge

diff --cc src/common/perf_counters.h
Simple merge

diff --cc src/rgw/driver/rados/rgw_data_sync.cc
Simple merge

diff --cc src/rgw/driver/rados/rgw_rest_log.cc
Simple merge