Only dump the used/unused parameter yaml files when *not* restarting a run

This is a trivial change but thought you may have a better suggestion.

I am actually surprised we haven't seen issues with this yet since all ranks were attempting to write.

Agreed... I've checked these files from time to time and never seen any garbled output. Must be fast to write and close and each process went past at slightly different times, so no simultaneous opens (alternatively I wonder what the IO buffering does when you open a file, and only flush to it on close, the contents is less than 4096 characters, so probably looks like a single write).

No better ideas, so accepting.

merged

mentioned in commit 2b948447