Revert "ixfr: Fixed fallback to AXFR for AXFR-style IXFR."

This reverts commit e774c8a835a500cd0e66d561aa8e9f217a372f47.
IXFR: AXFR-style IXFR client side handling
tests-extra: Test for multimessage AXFR-style IXFR
Merge branch 'axfr-ixfr-client' into 'master'

Axfr ixfr client

See merge request !280