Remove AERI feature and associated documentation

AERI has been shutdown by eclipse foundation: https://bugs.eclipse.org/bugs/show_bug.cgi?id=551898
AERI feature has been removed in 2020-03 simultaneous release: https://bugs.eclipse.org/bugs/show_bug.cgi?id=561089

On JBoss side, AERI is not bundled anymore starting from 4.15.0.AM1.
The target URL used to report errors leads to a 404: https://tools.jboss.org/usage/errors/rest/2.0/community/discovery
All dependencies should be removed ( plugin.xml, direct dependencies from features/Manifest ).
All documentation on JBoss side should also be removed in the future :
https://tools.jboss.org/ -> Call for participation paragraph on the bottom page that forward to https://tools.jboss.org/usage/#error-reporting web page