Increase timeouts for some nutils test cases

[MakisH]

Triggered by #745

[MakisH]

A test works for all but the two-scale-heat-conduction case, which fails for a known unrelated issue (see #852, which needs a new release of the micro-manager.

The times required were:

• channel-transport_fluid-nutils_transport-nutils: 140s
• channel-transport-particles_fluid-nutils_particles-mercurydpm: 82s
• two-scale-heat-conduction: (error)

The cases from #745 were all killed at 190s, which raises questions on whether that approach increases the runtime. In any case, I want to exclude Nutils from that PR.