intermittent segfaults when running allGather

[Sh0g0-1758]

As noted in #3886 in the comment, allGather segfaults when run with PE=128, nodes=1. This could be an error in the charm runtime itself but this needs to be investigated.

[ericjbohm]

These symptoms often arise due to a memory bug. Have you tried analyzing the code using a memory analysis tool like address sanitizer or valgrind?

[stwhite91]

Have you reproduced the issue on the version of the allgather code that was merged to main?