Switch to new dune-alugrid module

For 2.4, we will only support the new dune-alugrid module and remove support for ALUGrid 1.52.

That still needs to be done, though.

dune-pdelab#2 (closed) tracks the same task for PDELab itself.

Added ~24 label

This is on hold until dune-pdelab#3 (closed) is resolved.

Added ~25 label

mentioned in merge request !1 (merged)

Status changed to closed by commit 4bd02e32