more time for clean shutdown
more time for clean shutdown

* wait 12 minutes before sending SIGTERM to entire process group
* wait 15 minutes before sending SIGKILL to entire process group

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