update timer

[tdcwilliams]

we are stuck on boost 1.74 since we use a deprecated timer implementation
we need to:

• switch from boost/mpi/timer.hpp to boost/timer/timer.hpp as stated in the deprecation notices ie

  #include <boost/timer/timer.hpp> // Update this include
  #include <boost/mpi.hpp> // Ensure MPI support is included
  

• change timer instantiation: change boost::mpi::timer() to boost::timer::cpu_timer() or boost::timer::wall_timer() (perhaps choose the same as nextsim-dg)

[einola]

We don't need to do what you list in the second bullet point to upgrade boost. I propose that we do

• Hotfix to address the first bullet (I'll do that now)
• Address the second bullet in develop by changing all timers to boost::mpi::timer (and get rid of boost::timer and boost/timer/timer.hpp).