chore: reinstate repack

[DhairyaLGandhi]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Add any other context about the problem here. solves #1146

[DhairyaLGandhi]

@AayushSabharwal could the restructure adjoint have introduced the failures in Core 5?

[AayushSabharwal]

The logs it's showing me are truncated to after line 5471, I can't see the error

[DhairyaLGandhi]

Perhaps this is more useful https://github.com/SciML/SciMLSensitivity.jl/actions/runs/11778287917/job/32804415075?pr=1147

[AayushSabharwal]

I don't think it's ArrayInterface.restructure. I added an error() in the adjoint, and it still gives the same result as CI.

[DhairyaLGandhi]

Both the reverse mode methods produce identical gradients, and has 6-7 digits off accuracy with the FD comparison.