[Rust-CI Follow-up] Re-enable build break on Clippy warnings

[drewrelmas]

With the introduction of some donated Rust components into the repository, some modification to donated workflow yamls was required for initial CI enablement (#302) in this repository.

In this case, when first trying out clippy linting, noticed that there were 8 identified warnings already present in the code. It is likely that updates to the clippy linter since initial commit of that code led to these warnings surfacing after the fact.

For the moment, #302 removed the Clippy args -- -D warnings which cause warnings to break the build. Once the existing warnings are resolved, should re-add -- -D warnings.

[drewrelmas]

Clippy args -- -D warnings has been reintroduced in #523 with the exception of beaubourg subfolder. That is a reference implementation that will not be receiving new development, so it is excluded from this strictness.