MLFlow logger: log system metrics for all nodes when rank_zero_only is True #3905
Description
🚀 Feature Request
When setting rank_zero_only to True and setting log_system_metrics to True, the Mlflow logger should log system metrics for all nodes, these metrics are all logged into the MLflow run created by Rank-0, and the metric keys are grouped by node IP.
Motivation
In current Composer MLflow logger implementation, if setting rank_zero_only to True and setting log_system_metrics to True, the system metrics are only logged in the first node. Then user can't view the system metrics of other nodes.