JBM MD handle is not needed except MASA

The JBM decoder metadata handle hJbmMetadata is allocated in all formats with EXT output configuration. However, it is needed in MASA and OMASA formats only and it thus consumes unnecessary memory in other formats.

The proposed fix limits the allocation of hJbmMetadata handle to MASA and OMASA only.

For records: the sizeof( JBM_METADATA ) is 3094 bytes which is thus saved in other than MASA/OMASA formats.