Hierarchical Grid - export to PDF exports incorrect child data.

[MayaKirova]

1. Open sample: https://staging.infragistics.com/products/ignite-ui-angular/angular/components/hierarchicalgrid/export-excel#angular-excel-exporter-example
2. Expand 1 root row (doesn't matter which one)
3. Expand 1 child row (doesn't matter which one)
4. Export to PDF

Data from the 2nd level of the hierarchy is duplicated for all child rows, for all row islands.

Example.

In Grid:

In PDF: