Refactor Telemetry Initialization and Environment Utilities (#811)

* improve code for metrics

* improve code for metrics

* fix

* fix

* Refactor telemetry initialization and environment functions ordering

- Reorder functions in envs.rs by type size (8-bit to 64-bit, signed before unsigned) and add missing variants like get_env_opt_u16.
- Optimize init_telemetry to support three modes: stdout logging (default error level with span tracing), file rolling logs (size-based with retention), and HTTP-based observability with sub-endpoints (trace, metric, log) falling back to unified endpoint.
- Fix stdout logging issue by retaining WorkerGuard in OtelGuard to prevent premature release of async writer threads.
- Enhance observability mode with HTTP protocol, compression, and proper resource management.
- Update OtelGuard to include tracing_guard for stdout and flexi_logger_handles for file logging.
- Improve error handling and configuration extraction in OtelConfig.

* fix

* up

* fix

* fix

* improve code for obs

* fix

* fix

crates/audit/Cargo.toml

@@ -30,7 +30,9 @@ rustfs-targets = { workspace = true }
 rustfs-config = { workspace = true, features = ["audit", "constants"] }
 rustfs-ecstore = { workspace = true }
 chrono = { workspace = true }
+const-str = { workspace = true }
 futures = { workspace = true }
+metrics = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
@@ -39,5 +41,6 @@ tracing = { workspace = true, features = ["std", "attributes"] }
 url = { workspace = true }
 rumqttc = { workspace = true }
 
+
 [lints]
 workspace = true