remove checkBucketExist check entirely to avoid fan-out calls (#18917)

Each Put, List, Multipart operations heavily rely on making
GetBucketInfo() call to verify if bucket exists or not on
a regular basis. This has a large performance cost when there
are tons of servers involved.

We did optimize this part by vectorizing the bucket calls,
however its not enough, beyond 100 nodes and this becomes
fairly visible in terms of performance.

cmd/bitrot-streaming.go

@@ -90,7 +90,7 @@ func newStreamingBitrotWriterBuffer(w io.Writer, algo BitrotAlgorithm, shardSize
 }
 
 // Returns streaming bitrot writer implementation.
-func newStreamingBitrotWriter(disk StorageAPI, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.Writer {
+func newStreamingBitrotWriter(disk StorageAPI, origvolume, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.Writer {
 	r, w := io.Pipe()
 	h := algo.New()
 
@@ -110,7 +110,7 @@ func newStreamingBitrotWriter(disk StorageAPI, volume, filePath string, length i
 			bitrotSumsTotalSize := ceilFrac(length, shardSize) * int64(h.Size()) // Size used for storing bitrot checksums.
 			totalFileSize = bitrotSumsTotalSize + length
 		}
-		r.CloseWithError(disk.CreateFile(context.TODO(), volume, filePath, totalFileSize, r))
+		r.CloseWithError(disk.CreateFile(context.TODO(), origvolume, volume, filePath, totalFileSize, r))
 	}()
 	return bw
 }