[clippy] Fix potentially expensive `expect_fun_call` anti-pattern.

This came out of a chat with josephry@. I noticed my teams code
was calling format! during buffer deallocation and discovered a few
hundred across the tree of this anti-pattern.

Fixed with a manual edit to build/rust/clippy.gni followed by:
```
fx clippy --all --raw | fx shush --lint clippy::perf fix
```

Note that enforcement of this lint may require further discussion
first so it is not part of this CL.

Change-Id: Ia45b623684c86e2b3e543b33e178c5391b4f9e02
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/786893
Reviewed-by: Abdulla Kamar <abdulla@google.com>
Commit-Queue: Aaron Drew <ripper@google.com>
70 files changed
tree: 837e3d61b1bfae9d449d5ba6f394ff9b0be16a5a
  1. boards/
  2. build/
  3. bundles/
  4. docs/
  5. examples/
  6. products/
  7. scripts/
  8. sdk/
  9. src/
  10. third_party/
  11. tools/
  12. zircon/
  13. .clang-format
  14. .clang-tidy
  15. .editorconfig
  16. .git-blame-ignore-revs
  17. .gitattributes
  18. .gitignore
  19. .gitmodules
  20. .gn
  21. .style.yapf
  22. analysis_options.yaml
  23. AUTHORS
  24. BUILD.gn
  25. CODE_OF_CONDUCT.md
  26. CONTRIBUTING.md
  27. fuchsia.code-workspace
  28. LICENSE
  29. OWNERS
  30. PATENTS
  31. pyrightconfig.json
  32. README.md
  33. rustfmt.toml
README.md

Fuchsia

What is Fuchsia?

Fuchsia is an open source, general purpose operating system supporting modern 64-bit Intel and ARM processors.

We expect everyone interacting with our project to respect our code of conduct.

Read more about Fuchsia's principles.

How can I build and run Fuchsia?

See Getting Started.

Where can I learn more about Fuchsia?

See fuchsia.dev.