fs: Remove a couple debug logs

[nicholasbishop]

The trace log in open can be a bit misleading since at first glance it looks like an error, but in some cases it's expected for open to fail, like when calling try_exists.

The debug log in create_dir_all is showing internal details so probably not all that useful to end users.

Checklist

• Sensible git history (for example, squash "typo" or "fix" commits). See the Rewriting History guide for help.
• Update the changelog (if necessary)

[nicholasbishop]

I debated a bit here as to whether it might be better to go the other direction here, and add more logs at trace or debug level, e.g. on each entry to open we could trace the path and other parameters. In other parts of the uefi crate we have very little logging, so went with removing -- but I'd be open to a different approach.

(My main motivation for this change is that I spent a little time being confused about why I was getting a file-open error, until I realized it was trace logging happening when calling write on a new file; write calls try_exists, which calls open.)

[phip1611]

I'm in favor of removing them. The interface seems to be stable enough (no bug reports in the last couple of months), so we can also remove this very verbose logging - especially as it results in confusions