EventSourceLoggerProvider allocates *ALOT*

[davidfowl]

Looking at some 3.0 memory profiles, it seems as though the event source logger we added by default in 2.2 increases the amount of pressure we put on the GC.

This application made ~67000 requests:

These are the top per request allocations (by size):

The boxed Int32, the Object[], the KeyValuePair<string, string>[], the List<KeyValuePair<string, string>> the EventSource.EventSourceLogger+ActivityScope all come from the EventSourceLogger and the LoggingEventSource.

Here a view from the allocation callsites:

We need to investigate this and avoid this many allocations.

cc: @pakrym

[pakrym]

I've improved no-op logging *ALOT* and improved subscriber case. A lot of allocations are internal to EventSource.

[muratg]

Looks like improvements were done here. @davidfowl if you'd like more focus on this, please reactivate.