Reduce amount of logging from #[instrument]

[ysaito1001]

Will be merged to smithy-rs-release-0.56.x branch

Addresses awslabs/aws-sdk-rust#872

Motivation and Context

With the introduction of the orchestrator, the core functions that live in aws-smithy-runtime/src/client/orchestrator.rs were annotated by #instrument. By default this emits logs at the INFO level, which caused our customer to see the excessive amount of logging after switching to the latest SDK creates 0.29.

Description

This PR reduces the log level to DEBUG wherever we use #instrument throughout the file.

Testing

No new tests have been added as part of this PR. An enhancement has been filed to check logging volume.

Here is a quick check that all instances in the file specify trace:

✗ rg "instrument"
src/client/orchestrator.rs
34:use tracing::{debug, debug_span, instrument, trace, Instrument};
160:    .instrument(debug_span!("invoke", service = %service_name, operation = %operation_name))
167:#[instrument(skip_all, level = "debug")]
186:#[instrument(skip_all, level = "debug")]
319:#[instrument(skip_all, level = "debug")]
389:                .instrument(debug_span!("read_body"))
398:    .instrument(debug_span!("deserialization"))
407:#[instrument(skip_all, level = "debug")]
419:#[instrument(skip_all, level = "debug")]

Checklist

• I have updated CHANGELOG.next.toml if I made changes to the smithy-rs codegen or runtime crates
• I have updated CHANGELOG.next.toml if I made changes to the AWS SDK, generated SDK code, or SDK runtime crates

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Client Test
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.