[EventPipe] Handle EventPipe Enable calls during shutdown

[mdh1418]

Fixes #103480

[mdh1418]

I'm wondering, would there be another way to detect shutdown and avoid attempting to enable the eventpipe session?
Would it be possible to detect whether or not shutdown is in progress and then deem it unnecessary to call disable events in CallDisableEventsIfNecessary?

Would guarding EventPipeAdapter::StartStreaming and CommitDispatchConfiguration code paths from a failed session enable silently some paths where we would want to bubble up that the eventpipe session failed to enable?

[noahfalk]

LGTM

There is still some remaining fishy behavior shown in #103480 that would be good to address in other PRs.

• The crash that occurs when the EventListener is not disposed
• We called EventListener.DisableEvents() but somehow that is being translated into a call to EventPipeInternal.Enable().

[davmason]

LGTM, thanks!