Set custom limit on API call for Export to Excel in ListReport template.

[ParvKhatri]

We are experiencing gateway time outs while utilizing the export button from the Fiori Elements List Report. This is due to Export Request Size dynamically considering 5000 records for each call based on data volume, such as in a customer environment with 200,000 users. Processing 5000 records for each service call takes more than 30 seconds, causing the gateway timeout. 
We're attempting to set the exportRequestSize to 3000 in the manifest.json, but it is not being considered. Please let us know how to modify the exportRequestSize.

Here is the code we customized:

We can have call if you need more information.

Here is the UI screenshot for export icon that we are using.

Thank you in advance.