Fix EZP-23580: FOSHttpCache always matches default site with urielement matcher

> https://jira.ez.no/browse/EZP-23580

Bug introduced by #1025 ([EZP-22400](https://jira.ez.no/browse/EZP-22400)).
SiteAccess matching was always triggered for user hash requests, which should never happen.

This PR fixes it.
Tests: Unit test added.
EZP-23580: Added full test coverage for SiteAccessMatchListener
Fix EZP-23387: Move image variation config for ezdemo to DemoBundle

> https://jira.ez.no/browse/EZP-23387
> https://jira.ez.no/browse/EZP-23382

Tests have been updated.
Image variations are now dumped for non-ezdemo packages only.

See also [EZP-23382](https://jira.ez.no/browse/EZP-23382). Default image aliases are reduced to the minimum.