fix: multipart replication and encrypted etag for sse-s3 (#13171)

Replication was not working properly for encrypted
objects in single PUT object for preserving etag,

We need to make sure to preserve etag such that replication
works properly and not gets into infinite loops of copying
due to ETag mismatches.

cmd/encryption-v1.go

@@ -68,10 +68,10 @@ const (
 
 )
 
-// isEncryptedMultipart returns true if the current object is
+// isMultipart returns true if the current object is
 // uploaded by the user using multipart mechanism:
 // initiate new multipart, upload part, complete upload
-func (o *ObjectInfo) isEncryptedMultipart() bool {
+func (o *ObjectInfo) isMultipart() bool {
 	if len(o.Parts) == 0 {
 		return false
 	}
@@ -427,7 +427,7 @@ func DecryptBlocksRequestR(inputReader io.Reader, h http.Header, seqNumber uint3
 
 	bucket, object := oi.Bucket, oi.Name
 	// Single part case
-	if !oi.isEncryptedMultipart() {
+	if !oi.isMultipart() {
 		var reader io.Reader
 		var err error
 		if copySource {
@@ -589,7 +589,7 @@ func (o *ObjectInfo) DecryptedSize() (int64, error) {
 	if _, ok := crypto.IsEncrypted(o.UserDefined); !ok {
 		return 0, errors.New("Cannot compute decrypted size of an unencrypted object")
 	}
-	if !o.isEncryptedMultipart() {
+	if !o.isMultipart() {
 		size, err := sio.DecryptedSize(uint64(o.Size))
 		if err != nil {
 			err = errObjectTampered // assign correct error type
@@ -732,7 +732,7 @@ func (o *ObjectInfo) GetDecryptedRange(rs *HTTPRangeSpec) (encOff, encLength, sk
 	// Assemble slice of (decrypted) part sizes in `sizes`
 	var sizes []int64
 	var decObjSize int64 // decrypted total object size
-	if o.isEncryptedMultipart() {
+	if o.isMultipart() {
 		sizes = make([]int64, len(o.Parts))
 		for i, part := range o.Parts {
 			var partSize uint64