Steps to reproduce:

1. Clean installation of Ibexa DXP.
2. Create content with at least one image as a content field value.
3. Go to the full view page of the content, which displays the image field value using `ibexa_image_alias` Twig function.
4. Observe the image alias services being called.
5. Refresh the full view page.
6. Observe the image alias services being called.

Result:

On every page refresh `Ibexa\Bundle\Core\Imagine\Variation\ImagineAwareAliasGenerator` service is being called which access and check filesystem for an image binary file.

Expected result:

Only the first page load should trigger `Ibexa\Bundle\Core\Imagine\Variation\ImagineAwareAliasGenerator` service and access binary file. Every next page reload should call `Ibexa\Bundle\Core\Imagine\Cache\AliasGeneratorDecorator` service and serve the image alias from a cache.

Additional details:

It seems that `Ibexa\Bundle\Core\Imagine\ImageAsset\AliasGenerator` (which uses cache decorator class inside) is being registered with the same tag identifier as `Ibexa\Bundle\Core\Imagine\Variation\ImagineAwareAliasGenerator`. This causes AliasGenerator to be overridden by ImagineAwareAliasGenerator inside VariationHandlerRegistry.