Update mercury and drop margo handles patch

Since mercury fixed the issue on their code [1], we can drop the
temporary patch we were using to avoid handles reset.

Due to the mercury fix The follwing two issues have been solved:
 - Mercury: https://github.com/mercury-hpc/mercury/issues/272
 - Margo: https://xgitlab.cels.anl.gov/sds/margo/issues/47

[1]: https://github.com/mercury-hpc/mercury/commit/9512b8b04c265645f95fd99f3b9c015e836c0347