With the WT-15002 and WT-15003 merged, we should be able to run prepare and preserve prepare config in test format for disagg. Let's enable that.
WT-15051 Search near fails due to unset key (prepare txns and disagg)
WT-15002 Remove the WT_DELTA_CELL_LEAF structure and change leaf page delta format
WT-15003 Remove the WT_DELTA_CELL_INT structure and pack internal page deltas with WT_CELL