feat(server-utils): Emit execute_tool spans for Anthropic's beta.sessions.events.toolRunner() #25446

#25320 instruments beta.messages.toolRunner(), but the Managed Agents session runner, client.beta.sessions.events.toolRunner(sessionID, { tools }), runs tools too, and its tool calls get no spans. It runs each tool through runRunnableTool, which calls tool.run(input, { toolUse, toolUseBlock, signal }) and turns any throw into an error result, so a failing tool is also invisible to the app. A tool only gets a span today if the same object was also passed to beta.messages.toolRunner().

The contract is the same run(input, ctx) the messages runner uses, so the wrapping from #25320 should carry over. The new part is hooking sessions.events.toolRunner() on both the orchestrion and instrumentAnthropicAiClient paths, and checking whether tools added to a running session reach run without going through its options.

Follow-up to #25288 and #25320.