Leapfrog fix

[brryan]

PR Summary

The particle_leapfrog_outflow test is currently breaking CI intermittently.

I think the issue is that, for zero particles on a rank, we don't initialize all send_sizes to 0 so sometimes they're full of garbage. This PR seems to cycle correctly.

PR Checklist

• Code passes cpplint
• New features are documented.
• Adds a test for any bugs fixed. Adds tests for new features.
• Code is formatted
• Changes are summarized in CHANGELOG.md
• Change is breaking (API, behavior, ...)
  • Change is additionally added to CHANGELOG.md in the breaking section
  • PR is marked as breaking
  • Short summary API changes at the top of the PR (plus optionally with an automated update/fix script)
• CI has been triggered on Darwin for performance regression tests.
• Docs build
• (@lanl.gov employees) Update copyright on changed files

[brryan]

OK there's an additional issue which is that our sort() command is currently disabled for HIP. I'm going to see if I can't fix this

[pgrete]

OK there's an additional issue which is that our sort() command is currently disabled for HIP. I'm going to see if I can't fix this

This should be fixed with Kokkos 4.4 which has support for sorting on hip (though the interface would need to be updated).

[brryan]

OK there's an additional issue which is that our sort() command is currently disabled for HIP. I'm going to see if I can't fix this

This should be fixed with Kokkos 4.4 which has support for sorting on hip (though the interface would need to be updated).

Yes agreed, I can make a separate WIP PR to switch to Kokkos::sort() after we upgrade parthenon to Kokkos 4.4