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/profiling-commands.go

@@ -54,7 +54,7 @@ func (adm *AdminClient) StartProfiling(profiler ProfilerType) ([]StartProfilingR
 	v := url.Values{}
 	v.Set("profilerType", string(profiler))
 	resp, err := adm.executeMethod("POST", requestData{
-		relPath:     "/v1/profiling/start",
+		relPath:     adminAPIPrefix + "/profiling/start",
 		queryValues: v,
 	})
 	defer closeResponse(resp)
@@ -83,7 +83,7 @@ func (adm *AdminClient) StartProfiling(profiler ProfilerType) ([]StartProfilingR
 // DownloadProfilingData makes an admin call to download profiling data of a standalone
 // server or of the whole cluster in  case of a distributed setup.
 func (adm *AdminClient) DownloadProfilingData() (io.ReadCloser, error) {
-	path := fmt.Sprintf("/v1/profiling/download")
+	path := fmt.Sprintf(adminAPIPrefix + "/profiling/download")
 	resp, err := adm.executeMethod("GET", requestData{
 		relPath: path,
 	})