416 - Remove some trivial rust snippets

[OkelleyDevelopment]

After further reviewing of the Rust snippets we include, there were a number that could be removed. I chose a few that were mentioned in the issue and others I saw from testing. The second case was because it's faster to type it out than it was to wait for the snippet engine to load them.

Notes for reviewers

• Feel free to suggest others we should remove
• Also suggest if some should remain (that are currently removed).
• Closes 416

[oriongonza]

I in principle agree with all of them, but I would have been more aggressive.

We should also try to remove snippets covered already by r-a