change_streams_resume_at_same_clustertime.js should not assume same that multi-update across shards are performed at the same clusterTime

This check assumes that a multi-update that performed outside of a transaction, on sharded cluster, will result in all writes occurring at the same cluster time. This is an incorrect assumption as each write will be performed at the individual shard's cluster time. I believe we should change this check to be an assert.gte().