Fix deprecated curl_close() for PHP 8.5

in core/modules/page_cache/tests/src/Functional/PageCacheTest.php object is destroyed when leaving method
in core/tests/Drupal/FunctionalJavascriptTests/WebDriverCurlService.php setting to null

I wondered if we didn't have to replace it with anything else, but the commit linked here already mentions that it was already not working since php 8.0.

#[\Deprecated(since: '8.5', message: "as it has no effect since PHP 8.0")]

This looks good to me.

See no harm in back porting this one all the way to 10.5.x...

Committed 96e0b25 and pushed to 11.x. Thanks!
Committed f1bcab7 and pushed to 11.2.x. Thanks!
Committed 7497a37 and pushed to 10.6.x. Thanks!
Committed d6d33f2 and pushed to 10.5.x. Thanks!

andypost → closed merge request !12977