Stat clear is not clearing the proper lookaside cursor stats

Whenever the WT_STAT_CLEAR passed during the configuration of the connection, the statistics that are used from the lookaside cursors need to be reset. Instead of clearing the cursor statistics that are used, it reset other stats.

        WT_STAT_SET(session, dstats, cursor_insert, 0);

The proper cursor stat that needs to be reset is cursor_update instead of cursor_insert.