I'm not entirely sure what you mean by "the test results history" is the on-demand antivirus scan history ?
If so when creating a scan or using an existing one, you can customise the scan, so it doesn't create a report.
In the Scan Settings > Report File and uncheck the Generate report file. That said if the report file isn't created I believe there would be no data to compile the Scan History.
You could test this be deleting the report files from C:\ProgramData\AVAST Software\Avast\report, the report file has the default name of ScanName.txt, see attached images.