Fix EZP-21780: Map\URI siteaccess matcher is greedy

https://jira.ez.no/browse/EZP-21780

`Map\URI` is buggy when the siteaccess part appears in an URLAlias or link. 

Consider the following siteaccess match configuration:
```yaml
        match:
            Map\URI:
                eng: eng
```

When having a content with `/eng-foo-bar` URLAlias, the Map\URI matcher, which implements `URILexer` interface will remove the `/eng` part in the content's URLAlias, resulting to `-foo-bar`, which leads to a 404.

This PR fixes it and enriches corresponding test.

This should go to 5.2 IMHO since it's a very annoying issue with no workaround.