[Remote Publication] Streamline cleanup stats in the discovery stats

[Arpit-Bandejiya]

Is your feature request related to a problem? Please describe

Currently the stats for remote upload are like this:

"remote_upload": {
                        "success_count": 7,
                        "failed_count": 0,
                        "total_time_in_millis": 194,
                        "indices_routing_diff_files_cleanup_attempt_failed_count": 0,
                        "index_routing_files_cleanup_attempt_failed_count": 0,
                        "cleanup_attempt_failed_count": 0
                    },

Discussed in PR: #15291

Describe the solution you'd like

As we are adding more stats for cleanup, the idea is to decouple it from the remote upload.

Related component

ShardManagement:Placement

Describe alternatives you've considered

No response

Additional context

No response

[andrross]

[Catch All Triage - 1, 2, 3]