fix missing prop type issue (elastic#268713)

## Summary
Broke by elastic#268205 + elastic#268189

Author: delanni

x-pack/platform/plugins/shared/agent_builder/server/tracing/register_tracing.test.ts

@@ -230,6 +230,7 @@ describe('registerTracingExporter', () => {
       send_to_self: true,
       exporters: [],
       scheduledDelay: 100,
+      opik_distributed_tracing: false,
     };
 
     const teardown = await registerTracingExporter({ core: coreStart, tracingConfig, logger });