Convergence behavior of electrostatic solver changes whether embedded boundary support is on or off

[jwestern]

If I compile WarpX with embedded boundary support turned on, the electrostatic solver readily fails to converge.

If I recompile with embedded boundary support turned off, these struggles go away.

This is without even using embedded boundaries.

I don't have a minimal reproducer, and I can't provide my example as it contains proprietary information. Hoping someone else noticed this issue, or knows a simple way to reproduce it.

[WeiqunZhang]

The difference might be semi-coarsening, which is not supported in the multigrid solvers when EB is on.

[ax3l]

Weiqun's answer is the correct one, we currently (?) do not use the same solvers with or without EB. We currently have no semi-coarsening with EBs.

This is without even using embedded boundaries.

Just FYI, slightly related: @jwestern please see #5103 & #4865