Empty export result when pagination is hidden in datagrid

[hvanoch]

Summary
When exporting a datagrid, if the option hide: true is set, the export is empty for csv type. (an error is raised when using XLSX)

Steps to reproduce
Create a datagrid with options:

datagrids:
    [name]:
        options:
            toolbarOptions:
                pagination:
                    hide: true
            export: true

Export the grid in csv format

Actual Result
empty csv file

Expected Result
records exported

Details about your environment

• OroPlatform version: 4.2
• PHP version: 7.4
• Database (MySQL, PostgreSQL) version: MySql 8.0

The reason why the file is empty is because $this->totalCount = $gridData->getTotalRecords(); returns 0 in src/Oro/Bundle/DataGridBundle/ImportExport/DatagridExportConnector.php method ensureSourceDataInitialized