Improve memory management in DataTable/CSV #19158

We are seeing this error occur more regularly now, particularly with CSV format. It tends to appear more when there are visits with many actions, forms, media, etc.

{
    "type": 1,
    "message": "Out of memory (allocated 1982181376) (tried to allocate 163840 bytes)",
    "file": "/var/www/html/core/DataTable/Renderer/Csv.php",
    "line": 199,
    "request_id": "4ad9e",
    "backtrace": " on /var/www/html/core/DataTable/Renderer/Csv.php(199)\n",
    "safemode_backtrace": "<a href='/0'>#0</a> [internal function]: Piwik\\Plugins\\Cloud\\Controller->safemode(Array)\n<a href='/1'>#1</a> /core/FrontController.php(626): call_user_func_array(Array, Array)\n<a href='/2'>#2</a> /core/FrontController.php(168): Piwik\\FrontController->doDispatch('Cloud', 'safemode', Array)\n<a href='/3'>#3</a> /core/FrontController.php(99): Piwik\\FrontController->dispatch('CorePluginsAdmi...', 'safemode', Array)\n<a href='/4'>#4</a> /core/FrontController.php(274): Piwik\\FrontController::(Array)\n<a href='/5'>#5</a> [internal function]: Piwik\\FrontController::triggerSafeModeWhenError()\n<a href='/6'>#6</a> {main}"
}

Also listing the API calls here in case these are helpful :)

GET: {
    "module": "API",
    "format": "TSV",
    "idSite": "229",
    "period": "range",
    "date": "2022-04-11,2022-04-15",
    "method": "Live.getLastVisitsDetails",
    "filter_limit": "10000",
    "expanded": "1",
    "translateColumnNames": "1",
    "language": "en",
    "token_auth": "XYZANONYMIZED",
    "force_api_session": "1",
    "format_metrics": "bc"
}

POST: {
    "token_auth": "XYZANONYMIZED",
    "module": "API",
    "format": "TSV",
    "idSite": "229",
    "period": "range",
    "date": "2022-04-11,2022-04-15",
    "method": "Live.getLastVisitsDetails",
    "filter_limit": "10000",
    "expanded": "1",
    "translateColumnNames": "1",
    "language": "en",
    "force_api_session": "1",
    "format_metrics": "bc"
}

Hi @JasonMortonNZ
Are you able to reproduce that? Could you maybe check if this changes solve that maybe:
https://github.com/matomo-org/matomo/compare/improvecsvexport?expand=1