Disable stacks on Debugger IPC events

[tommcdon]

We have received complaints from internal teams that app can crash when entering break state with Debugger IPC ETW events enabled. I was able to reproduce the issue by using perfview to enable .NET ETW events, F5 a .NET Core, and enter break state by hitting a breakpoint. The root issue is related to stackwalking on the Debugger IPC event causing a crash in the runtime. As the stack traces on Debugger IPC events is not useful in any production scenario, this PR disables the stackwalk on the IPC event.

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[noahfalk]

The root issue is related to stackwalking on the Debugger IPC event causing a crash in the runtime

Do we know why it crashes? Its not obvious to me why a crash in stackwalking would only be a problem for debugger related ETW events rather than all ETW events.

[tommcdon]

Do we know why it crashes?

Only that the stackwalker crashes on this one Debugger IPC event. Disabling the stackwalker successfully works around the issue. An internal partner team verified the fix.

[noahfalk]

Adding a little bit of detail from chatting with Tom offline...

Although we don't have the dump handy any more to dig into the details, there was some evidence that the stackwalk failed because there was a breakpoint on the callstack. Debugger events are the only time we'd expect ETW events to find a breakpoint on the stack so we don't expect the stackwalking issue to be problematic anywhere else. A partner team also ran with the proposed fix for weeks and confirmed experimentally no other problems were showing up.