Change the default value of The_Pinned_Arena release threshold (#3479)

The old default of the size of device memory is too big for some
machines (e.g., Perlmutter 80 GB nodes). Some WarpX runs were out of
memory during restart. It is now set to half of the device memory.

Src/Base/AMReX_Arena.cpp

@@ -282,7 +282,7 @@ Arena::Initialize ()
 #ifdef AMREX_USE_SYCL
  the_arena_init_size = std::min(the_arena_init_size, Gpu::Device::maxMemAllocSize());
 #endif
- the_pinned_arena_release_threshold = Gpu::Device::totalGlobalMem();
+ the_pinned_arena_release_threshold = Gpu::Device::totalGlobalMem() / Gpu::Device::numDevicePartners() / 2L;
 #endif
 
  ParmParse pp("amrex");