Remove Seam2 integration

We provide a org.jboss.integration.ext-content module which includes a org.jboss.seam.integration:jboss-seam-int-jbossas jar.

I suspect no active WildFly developers even know what that jar does or where it comes from. As discussed in WFLY-443 (open since 2013) there is no testing of this integration. Seam itself had significant use of Java EE APIs, which will not work in WildFly 27 or later. (The jboss-seam-int-jbossas itself has no use of javax.* classes, but that doesn't mean it's possible to integrate Seam applications, as those apps would need a jakarta.* namespace Seam.)