Ocassional timeout for build-test-other with stress copying

[qinsoon]

Both the following two runs timed out with 6 hours.
https://github.com/mmtk/mmtk-julia/actions/runs/11265384788/attempts/1
https://github.com/mmtk/mmtk-julia/actions/runs/11265384788/attempts/2

The third run passed within 2 hours.