Update ra_metrics family for Ra counters

[mkuratczyk]

PR rabbitmq/rabbitmq-server#13895 switches from exposing ra_metrics ETS table values as Prometheus metrics, to exposing Ra counters from seshat. There's many more metrics available with this change.
A few metrics are the same but have a slightly different name. Since the old name was incorrect, we don't maintain compatibility but use this opportunity to fix the name:

These metrics lost the _log part, since they are not log related:

• rabbitmq_detailed_raft_log_snapshot_index -> rabbitmq_detailed_raft_commit_index
• rabbitmq_detailed_raft_log_last_applied_index -> rabbitmq_detailed_raft_last_applied_index
• rabbitmq_detailed_raft_log_commit_index -> rabbitmq_detailed_raft_commit_index

rabbitmq_detailed_raft_term_total is now rabbitmq_detailed_raft_term. It was a bug that led to adding the _total suffix.