[release/5.0-rc2] Fix System.Net.Sockets telemetry

[MihaZupan]

Backport of #42188 to release/5.0-rc2
Fixes #41670

Customer Impact:

Bugs in new 5.0 telemetry (built mainly for YARP).

• Sockets telemetry events are broken when Connect/Accept finishes asynchronously (which is majority of cases) -- the Stop event won't be correlated with Start event. Observers of the events won't be able to associate connection failures, or time it took to establish TCP connections -- important scenarios, e.g. for YARP.
• NameResolution (DNS) telemetry events break following events of the HTTP request by making them appear as part of the NameResolution scope instead of following after it. It leads to cumbersome reading of following events, making end-to-end tracing hard to understand.

Testing

• Added a significant amount of testing to ensure the proper events and counters are emitted as part of this change.
• There are a lot of existing tests covering Sockets behavior in CI.
• End-to-end manual validation in PerfView and using in-proc EventListener.

Risk

• Small - There is a minimal impact on the non-Telemetry code path -- just moving part of code into a function. Majority of the changes are under IsTelemetryEnabled() check.
• Telemetry code paths are brand new - added during 5.0 (end of June), not yet consumed by any customers (beyond potentially early experimentation)
• if this change would introduce new problems, they would be limited to scenarios where telemetry is enabled.

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[MihaZupan]

/azp run runtime-libraries-coreclr outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[MihaZupan]

Test failures unrelated: #41606, #40798, #41953, #41929, #41531

[karelz]

We are ready for merge once approved by Tactics.