The "Init Duration" reported by the RIE is wrong

[simonis]

The "Init Duration" reported by the RIE is much too small. It is taken before the actual language runtime is even started:

	initStart, initEnd := InitHandler(sandbox, functionVersion, timeout, bs)

Instead, the end of the Init phase should be recorded when the sendInitRuntimeDoneLogEvent() is posted:

	defer func() {
		sendInitRuntimeDoneLogEvent(execCtx, sbInfoFromInit.SandboxType, runtimeDoneStatus)
	}()

[roger-zhangg]

Thanks for reporting @simonis We would appreciate if you already have some idea on the fix and we will be glad to review them

[JayYarlagadda]

Hi, I would like to work on this. I traced the current init path and plan to first add a regression test with delayed runtime initialization, then correct the timing boundary so Init Duration covers initialization through runtime readiness rather than ending early. I will keep the change focused and run make integ-tests-and-compile before opening the PR. Please let me know if you expect a different timing boundary.