Get rid of all `cores` without `mem` in the database

Rules like [this for raxml](https://github.com/galaxyproject/tpv-shared-database/blob/957d87883dde0c32f155da7634fb518b695a8866/tools.yml#L2277) allocate additional cores but because most people set `mem: cores * SOME_FACTOR` in their default tool it also scales memory, which is unnecessary for tools that parallelize well but don't use much memory.

We should probably run down the list of tools in the DB that only set `cores` and set `mem` as well unless they should actually scale memory lineraly with cores (and it should be roughly 4 GB/core, which is what most of us use I believe).