add test_time back

[quaquel]

As evidenced by #2350 and #2359, its rather useful to keep testing this even though it is deprecated.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🟢 -4.8% [-6.1%, -3.5%]	🔵 -0.3% [-0.5%, -0.2%]
BoltzmannWealth	large	🔵 -0.7% [-1.1%, -0.3%]	🟢 -8.3% [-8.6%, -7.9%]
Schelling	small	🔵 -1.8% [-2.3%, -1.3%]	🔵 -0.6% [-0.9%, -0.4%]
Schelling	large	🔵 -1.9% [-3.2%, -0.5%]	🟢 -7.9% [-9.8%, -5.8%]
WolfSheep	small	🔵 +0.0% [-0.1%, +0.2%]	🔵 +0.3% [+0.1%, +0.5%]
WolfSheep	large	🔵 -3.1% [-3.9%, -2.3%]	🟢 -6.7% [-8.7%, -4.3%]
BoidFlockers	small	🔵 +1.9% [+1.3%, +2.5%]	🔵 +0.2% [-0.3%, +0.7%]
BoidFlockers	large	🔵 +2.7% [+1.9%, +3.5%]	🔵 +0.8% [+0.2%, +1.3%]

[quaquel]

I know why the tests are breaking, but I have run out of time now to fix them all. Will pick this up later today.

[quaquel]

All unit tests are now fixed. This is ready to be merged

[Corvince]

great, thank you!

[EwoutH]

Awesome, thanks!