etw: fix descriptors of events 9 and 23

Pull Request check-list

• Does make -j8 test (UNIX) or vcbuild test nosign (Windows) pass with this change (including linting)?
• Is the commit message formatted according to [CONTRIBUTING.md][0]?
• If this change fixes a bug (or a performance problem), is a regression test (or a benchmark) included?

Affected core subsystem(s)

ETW

Description of change

A log of ETW events can be produced with:

logman start NodejsDCS -p NodeJS-ETW-provider -o node_log.etl -ets
:: Do something with node.exe
logman stop NodejsDCS -ets

The resulting etl file can be open in Event Viewer. However, ETW events 9 and 23 fail to display the EventData (under the Details tab), having instead a ProcessingErrorData section with the data in raw hexadecimal. This happens because the events are not generated correctly.

• Event 9: The last event descriptor is a string, but the string is published without the zero terminator. This seems to have been a mistake introduced when reviewing the original pull request, because the original code seems to include the terminator.
• Event 23: The event has no descriptors in the manifest (no template attribute), but is generated from node with a dummy integer descriptor, always equal to 0.

There are two commits for easy review, I plan to squash and use the following commit message:

etw: fix descriptors of events 9 and 23

Event 9 must include the string terminator in the last descriptor.
Event 23 must be published with no descriptors, in accordance with
the manifest.

cc @nodejs/platform-windows