When test_metrics_are_zero() is failing, that can be due to a stuck fragment (e.g.
IMPALA-9842). It was very useful to have a minidump of the Impalads when debugging IMPALA-9842. In addition to the memz and other debug pages, we should add code to produce a minidump.
One option is to use some of the code from bin/diagnostics/collect_diagnostics.py.