feat: dynamic enable or disable trace

[waynexia]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

Add a new HTTP API /debug/enable_trace to enable or disable trace on the fly.

❯ curl --data "true" 0:4000/debug/enable_trace
trace enabled%

❯ curl --data "false" 0:4000/debug/enable_trace 
trace disabled%

PR Checklist

Please convert it to a draft if some of the following conditions are not met.

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR requires documentation updates.
• API changes are backward compatible.
• Schema or data changes are backward compatible.

[Copilot]

Pull Request Overview

This PR introduces dynamic tracing control functionality, allowing administrators to enable or disable OpenTelemetry tracing at runtime through an HTTP API endpoint. The implementation refactors the existing tracing initialization to support reload capabilities and adds a new /debug/enable_trace endpoint.

• Adds HTTP API /debug/enable_trace for runtime trace control
• Refactors tracing initialization to support dynamic reload using tracing-subscriber's reload layer
• Renames existing reload handle from RELOAD_HANDLE to LOG_RELOAD_HANDLE for clarity

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/servers/src/http/dyn_trace.rs	New handler for dynamic trace control endpoint
src/servers/src/http/dyn_log.rs	Updates variable name to use renamed LOG_RELOAD_HANDLE
src/servers/src/http.rs	Registers new trace control endpoint and imports module
src/servers/Cargo.toml	Adds tracing-opentelemetry dependency
src/common/telemetry/src/logging.rs	Major refactor to support dynamic trace reload with new static handles
src/common/telemetry/src/lib.rs	Exports new static handles for trace control
src/common/telemetry/Cargo.toml	Uses workspace version for tracing-opentelemetry
docs/how-to/how-to-change-log-level-on-the-fly.md	Documents new trace control API
Cargo.toml	Adds tracing-opentelemetry to workspace dependencies

[Copilot]

Pull Request Overview

Copilot reviewed 9 out of 10 changed files in this pull request and generated 6 comments.

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[evenyag]

Others LGTM......

[killme2008]

@waynexia Do you have time to address the comments reviewed by coplit?

[killme2008]

Some comments reviewed by Copilot still need to be addressed.

LGTM overall.