feat(obs): enhance OpenTelemetry configuration and logging

Improve observability setup with the following changes:

- Replace static OnceCell with tokio::sync::OnceCell for guard management
- Add logger_level to OtelConfig for configurable tracing verbosity
- Improve telemetry initialization with better error handling
- Enhance logging filters and span configuration

Breaking Changes:
- Configuration now requires logger_level field
- Global guard management uses async-safe primitives

Example config:
observability:
  endpoint: "http://localhost:4317"
  logger_level: "debug"  # New required field

config/obs.example.toml

@@ -5,7 +5,8 @@ sample_ratio = 0.5
 meter_interval = 30
 service_name = "rustfs"
 service_version = "0.1.0"
-deployment_environment = "develop"
+environment = "develop"
+looger_level = "info"
 
 [sinks]
 [sinks.kafka] # Kafka sink is disabled by default