refactor: replace tracing-log with native tracing macros for guest log forwarding

[cshung]

Summary

Remove the tracing-log dependency from hyperlight-host and replace the format_trace/log::Record approach in outb_log with direct tracing event macros (error!, warn!, info!, debug!, trace!).

This consolidates guest log emission on the tracing crate, while preserving backward compatibility for consumers using only the log crate (via tracing's built-in log feature).

Changes

• src/hyperlight_host/Cargo.toml: Removed tracing-log dependency
• src/hyperlight_host/src/sandbox/outb.rs: Replaced format_trace/log::Record with native tracing macros matched on LogLevel
• src/hyperlight_host/tests/integration_test.rs: Switched use log::{error, trace} to use tracing::{error, trace}
• src/tests/rust_guests/simpleguest/src/main.rs: Switched log::info! to tracing::info! (kept log import for backward compat test)

Testing

• All unit tests pass (debug + release)
• All integration tests pass (debug + release)
• Clippy clean (debug + release)
• test_log_outb_log verifies backward compatibility with log-only consumers
• test_trace_outb_log verifies tracing subscriber path

Closes #1028

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR migrates guest/host logging paths away from log records + tracing-log formatting and toward emitting tracing events directly, while updating tests and dependencies accordingly.

Changes:

• Emit guest log messages in outb_log as structured tracing::* events instead of formatting a log::Record via tracing_log::format_trace.
• Replace some log macro usage/imports with tracing in guest and integration tests.
• Remove the tracing-log dependency from hyperlight_host.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

File	Description
src/tests/rust_guests/simpleguest/src/main.rs	Adjust imports and switch one traced log site to tracing::info!.
src/hyperlight_host/tests/integration_test.rs	Use tracing::{error, trace} instead of log::{error, trace}.
src/hyperlight_host/src/sandbox/outb.rs	Rework outb_log to emit tracing events with guest metadata as fields; update tests accordingly.
src/hyperlight_host/Cargo.toml	Drop tracing-log dependency.

[ludfjig]

Thanks for contribution! Would you mind also updating docs/hyperlight-metrics-logs-and-traces.md (remove any mention of tracing-log crate for exapmle). Thanks!

Eventually I want to get rid of all logging (non-tracing) code in both guest and host, so if you're up for doing something more relating to this topic we would greatly appreciate it!

[ludfjig]

Thank you!