build: remove "unused" debug property (alpha)
build: remove "unused" debug property (alpha)

Change build.xml file to remove the debug property that's no longer
needed or actually used, it's being overridden to always compile with
debug info.

thc202/zap-extensions,kingthorin/zap-extensions,thc202/zap-extensions,psiinon/zap-extensions,thc202/zap-extensions,kingthorin/zap-extensions,zaproxy/zap-extensions,zapbot/zap-extensions,kingthorin/zap-extensions,denniskniep/zap-extensions,veggiespam/zap-extensions,secdec/zap-extensions,zaproxy/zap-extensions,secdec/zap-extensions,veggiespam/zap-extensions,psiinon/zap-extensions,secdec/zap-extensions,kingthorin/zap-extensions,thc202/zap-extensions,denniskniep/zap-extensions,psiinon/zap-extensions,zapbot/zap-extensions,denniskniep/zap-extensions,denniskniep/zap-extensions,secdec/zap-extensions,veggiespam/zap-extensions,psiinon/zap-extensions,secdec/zap-extensions,zaproxy/zap-extensions,kingthorin/zap-extensions,psiinon/zap-extensions,zapbot/zap-extensions,zaproxy/zap-extensions,thc202/zap-extensions,psiinon/zap-extensions,zaproxy/zap-extensions,zaproxy/zap-extensions,denniskniep/zap-extensions,veggiespam/zap-extensions,veggiespam/zap-extensions,zapbot/zap-extensions,thc202/zap-extensions,zapbot/zap-extensions,zapbot/zap-extensions,denniskniep/zap-extensions,secdec/zap-extensions,kingthorin/zap-extensions,veggiespam/zap-extensions,secdec/zap-extensions