The prometheus metrics refractoring (#8003)

The measures are consolidated to the following metrics

- `disk_storage_used` : Disk space used by the disk.
- `disk_storage_available`: Available disk space left on the disk.
- `disk_storage_total`: Total disk space on the disk.
- `disks_offline`: Total number of offline disks in current MinIO instance.
- `disks_total`: Total number of disks in current MinIO instance.
- `s3_requests_total`: Total number of s3 requests in current MinIO instance.
- `s3_errors_total`: Total number of errors in s3 requests in current MinIO instance.
- `s3_requests_current`: Total number of active s3 requests in current MinIO instance.
- `internode_rx_bytes_total`: Total number of internode bytes received by current MinIO server instance.
- `internode_tx_bytes_total`: Total number of bytes sent to the other nodes by current MinIO server instance.
- `s3_rx_bytes_total`: Total number of s3 bytes received by current MinIO server instance.
- `s3_tx_bytes_total`: Total number of s3 bytes sent by current MinIO server instance.
- `minio_version_info`: Current MinIO version with commit-id.
- `s3_ttfb_seconds_bucket`: Histogram that holds the latency information of the requests.

And this PR also modifies the current StorageInfo queries

- Decouples StorageInfo from ServerInfo .
- StorageInfo is enhanced to give endpoint information.

NOTE: ADMIN API VERSION IS BUMPED UP IN THIS PR

Fixes #7873

pkg/madmin/heal-commands.go

@@ -208,7 +208,7 @@ func (adm *AdminClient) Heal(bucket, prefix string, healOpts HealOpts,
 		return healStart, healTaskStatus, err
 	}
 
-	path := fmt.Sprintf("/v1/heal/%s", bucket)
+	path := fmt.Sprintf(adminAPIPrefix+"/heal/%s", bucket)
 	if bucket != "" && prefix != "" {
 		path += "/" + prefix
 	}
@@ -280,7 +280,7 @@ type BgHealState struct {
 // current server or cluster.
 func (adm *AdminClient) BackgroundHealStatus() (BgHealState, error) {
 	// Execute POST request to background heal status api
-	resp, err := adm.executeMethod("POST", requestData{relPath: "/v1/background-heal/status"})
+	resp, err := adm.executeMethod("POST", requestData{relPath: adminAPIPrefix + "/background-heal/status"})
 	if err != nil {
 		return BgHealState{}, err
 	}