Remove unnecessary javadoc config from build/pom.xml

This is for WFLY-233 Move javadoc configuration into a separate module pom

Quite unfortunately, javadoc plugin needs it's data in the pom - no way to externalize.
The data are put to the pom by a script during javadoc creation, so they don't need to be here.
Nobody keeps them up to date anyway, so there's no reason to have them in that pom.xml.