Revert "Use Jetty 9.4.1"
Revert "Use Jetty 9.4.1"

This reverts commit cee6726e8814b2ebe094d47d3bef443b192bb50a.

vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa