…propagated (#2438)

This commit fixes the propagation of the `detailed-tracing-attributes`
flag to all necessary annotation structs and updates the templates to
correctly utilize the flag. See #2435 and #2252

For googleapis/google-cloud-rust#3239

Specifically:
- Adds `DetailedTracingAttributes` field to `modelAnnotations` and
`serviceAnnotations` in `annotate.go` to make the flag accessible in
`lib.rs.mustache` and service-level sections of `transport.rs.mustache`.
- Updates `annotateModel` and `annotateService` to populate the new
fields.
- Adds comprehensive unit tests in `annotate_test.go` to verify the
`DetailedTracingAttributes` flag is correctly set across
`modelAnnotations`, `serviceAnnotations`, `methodAnnotation`, and
`pathBindingAnnotation` based on the codec options.
- Modifies `lib.rs.mustache` to initialize the static
`INSTRUMENTATION_CLIENT_INFO` using `std::sync::LazyLock` to accommodate
the non-const `default()` function.
- Updates `transport.rs.mustache` to correctly dereference the
`LazyLock` when calling `with_instrumentation` (i.e.,
`&*crate::info::INSTRUMENTATION_CLIENT_INFO`).

These changes ensure that the conditional code blocks in both
`lib.rs.mustache` and `transport.rs.mustache` related to detailed
tracing are generated correctly based on the
`detailed-tracing-attributes` flag.

Tested:
- Ran `go test -race ./...` in the librarian repository to ensure all
unit tests pass, including new tests for flag propagation in
annotations.
- Manually regenerated the `google-cloud-showcase-v1beta1` client in a
local `google-cloud-rust` clone using the modified librarian:
1. With `--codec-option=detailed-tracing-attributes=true`: - Verified
`src/generated/showcase/src/lib.rs` contains the
`INSTRUMENTATION_CLIENT_INFO` static (using `LazyLock`). - Verified
`src/generated/showcase/src/transport.rs` includes
`.with_instrumentation(&*crate::info::INSTRUMENTATION_CLIENT_INFO)`
calls within the `if tracing_is_enabled` blocks in the `new` methods. -
Confirmed the crate builds and tests pass: `cargo build -p
google-cloud-showcase-v1beta1` `cargo test -p
google-cloud-showcase-v1beta1`
    2.  With the flag off (default):
        - Verified the above tracing-specific code is absent.
3. By setting `detailed-tracing-attributes = "true"` in
`src/generated/showcase/.sidekick.toml` and running refresh without the
codec option, confirming the config file is also respected.

…#2435)

Reverts #2252

My automated testing was wrong, it was happily disabled in both the
lib.rs and transport.rs because the feature flag wasn't propagated. I
have prepared a fix for the generator, but I'm finding this code
incorrect and so I'd like to revert if it can be done cleanly.