rgw: incremental data sync uses truncated flag to detect end of listing

rgw: incremental data sync uses truncated flag to detect end of listing

we call wait() after incremental sync if we've reached the end of the
datalog listing. the existing logic compares our local marker with the
remote's high marker, with some extra code to handle the case where the
remote log was trimmed

all of this can be simplified by using the 'truncated' flag returned
with the RGWReadRemoteDataLogShardCR used to list the remote datalog

Signed-off-by: Casey Bodley <cbodley@redhat.com>
(cherry picked from commit fb2b618658d8ff9c311838f59e396ab24c21e9e8)
Signed-off-by: Jonathan Brielmaier <jbrielmaier@suse.de>
Conflicts:
	src/rgw/rgw_data_sync.cc: write log with ldout