improve PresetTimeCallback

[albertomercurio]

This PR removes spurious memory allocations of PresetTimeCallback.

I tried to run the test locally, but I got

┌ Warning: Could not use exact versions of packages in manifest, re-resolving
└ @ Pkg.Operations ~/.julia/juliaup/julia-1.11.0+0.x64.linux.gnu/share/julia/stdlib/v1.11/Pkg/src/Operations.jl:1900
ERROR: Unsatisfiable requirements detected for package SciMLSensitivity [1ed8b502]:
 SciMLSensitivity [1ed8b502] log:
 ├─possible versions are: 7.0.0 - 7.68.0 or uninstalled
 ├─restricted to versions 7.68.0 - 7 by an explicit requirement, leaving only versions: 7.68.0
 └─restricted by compatibility requirements with DiffEqCallbacks [459566f4] to versions: uninstalled — no versions left
   └─DiffEqCallbacks [459566f4] log:
     ├─possible versions are: 4.0.0 or uninstalled
     └─DiffEqCallbacks [459566f4] is fixed to version 4.0.0

with both Julia 1.10 and 1.11.

This error shouldn't be related to this changes.

[albertomercurio]

Ok, now thee test was able to run, and everything is fine.

[ChrisRackauckas]

Rebase this so we can see the tests on LTS

[albertomercurio]

Ok done.