Update description of org.jboss.tools.cdi.xml and xml.ui plugins

This is a followup of JBDS-4495 . We deprecated seam 3 and moved it to central. We wanted to keep cdi itself still in the coretools feature.

But there are these two plugins:
org.jboss.tools.cdi.xml.ui_1.8.100.v20170801-1456.jar
org.jboss.tools.cdi.xml_1.8.100.v20170801-1421.jar

They don't have seam in the name, but their descriptions say:
JBoss Tools Seam XML
https://github.com/jbosstools/jbosstools-javaee/blob/master/cdi/plugins/org.jboss.tools.cdi.xml/plugin.properties#L2
Seam XML
https://github.com/jbosstools/jbosstools-javaee/blob/master/cdi/plugins/org.jboss.tools.cdi.xml.ui/plugin.properties#L2

Jeff checked the code and it doesn't seem like this has anything to do with Seam, so we should change the description.

I'm not sure myself what to call them