chore(model): remove redundant removal of internal fields in indexsender (#10173)

While it doesn't hurt, it's unnecessary since the big protobuf
modernisation, that also introduced types separate from the generated
ones for internal use. Those fields are already dropped when converting
to the wire in protocol.

lib/model/indexhandler.go

@@ -489,14 +489,8 @@ func prepareFileInfoForIndex(f protocol.FileInfo) protocol.FileInfo {
 	if f.IsReceiveOnlyChanged() {
 		f.Version = protocol.Vector{}
 	}
-	// The trailer with the encrypted fileinfo is device local, don't send info
-	// about that to remotes
+	// The trailer with the encrypted fileinfo is device local, announce the size without it to remotes.
 	f.Size -= int64(f.EncryptionTrailerSize)
-	f.EncryptionTrailerSize = 0
-	// never sent externally
-	f.LocalFlags = 0
-	f.VersionHash = nil
-	f.InodeChangeNs = 0
 	return f
 }