databases/cego: update 2.52.8 -> 2.52.9

• In CegoAdminHandler::getUserInfo, increased size of NUMREQ and NUMQUERY from 10 to 12, for long running systems with > 10^9 requests
• Added pack mode in CegoClient to improve the display of large string column values. Only the longest length of all values in <n> rows is displayed, not the full length of the field itself. Example: If the table definition for a string is 300 chars, and the values are only 4-10 chars wide, the table is only displayed with 10 chars.
• Fix added in CegoDistCursor::joinSetup: for outerCond calculation, null value comparisons are also used, since this leads to correct join results and can be optimized by using btrees. ( set attrCond.getFilterCond(outerSchema, false) to (outerSchema, true) for left outer and right outer join)
• In CegoSelect::getPlan, added parentJoinBuf setup for nested queries in expression list to evaluate join plan correctly ( parentJoinBuf is required for analysis in CegoQueryHelper::checkAttrCond)
• Add duplicate check for table aliases in CegoSelect::evalReferences