Allocation tests broken since Julia 1.9

[andreasnoack]

See e.g. https://github.com/JuliaDiff/ForwardDiff.jl/actions/runs/8194354842/job/22410181345. The allocations only appear when bounds checking is enables. In #688, I'm marking them as broken.

[devmotion]

We don't test 1.9 anymore, but on 1.10, 1.11 and 1.12 tests pass currently: https://github.com/JuliaDiff/ForwardDiff.jl/blob/master/test/AllocationsTest.jl