Bug#970864: dolphinx: flaky amd64 autopkgtest on ci.debian.net: regularly times out

[Drew Parsons]

Source: dolfinx
Followup-For: Bug #970864

Upstream have suggested running tests with
  DOLFINX_JIT_CFLAGS="-g0 -O0"
  
Bug-resolving progress is currently hampered by the llvmlite fiasco.