[BUGFIX][Oracle] Mixing SDO_GEOMETRY Point definition

Fixes #18900

In `sdoobj`, the `elem_info` array size is not the right way to defined the way
to read Point coordinate. The right way is to check the
sdoind attributes, like in Mapserver.

The way Mapserver defined check point coordinate: https://github.com/mapserver/mapserver/blob/fd04328a89e75ac963f15867d9d90a50d47513c1/maporaclespatial.c#L1588

(cherry-picked from 4017690)

Author: rldhont

src/providers/oracle/ocispatial/qsql_ocispatial.cpp

@@ -2402,19 +2402,13 @@ bool QOCISpatialCols::convertToWkb( QVariant &v, int index )
     return false;
   }
 
-  if ( iType == gtPoint && nElems == 0 )
+  if ( iType == gtPoint &&
+       sdoind->_atomic == OCI_IND_NOTNULL &&
+       sdoind->point.x == OCI_IND_NOTNULL &&
+       sdoind->point.y == OCI_IND_NOTNULL )
   {
     Q_ASSERT( nOrds == 0 );
 
-    if ( sdoind->_atomic != OCI_IND_NOTNULL ||
-         sdoind->point.x != OCI_IND_NOTNULL ||
-         sdoind->point.y != OCI_IND_NOTNULL )
-    {
-      qDebug() << "null point";
-      v = QVariant();
-      return true;
-    }
-
     double x, y, z = 0.0;
     if ( !getValue( &sdoobj->point.x, x ) )
     {