chore(dev): make -D warnings the default via .cargo/config.toml

[thomasqueirozb]

Summary

Move -D warnings from the CI setup action and vdev's explicit clippy args into the [target.'cfg(all())'] section of .cargo/config.toml. This makes warnings-as-errors the default for all targets and all cargo subcommands (build, test, clippy) in both local development and CI.

Previously, -D warnings was injected only for Linux targets in CI via a ~/.cargo/config.toml override, and passed explicitly to clippy via vdev. Now it's in one place and covers all platforms.

Vector configuration

NA

How did you test this PR?

NA

Change Type

• Bug fix
• New feature
• Dependencies
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

NA