[SNS Logging] [sf_emulator only] expired_session and timeout events get fired at the same time causing double closed_session logging

[ear-dev]

I'm not sure if we should remove session_expired or if we only need to handle it in a case that is not also a session_timeout, if there is such a thing.

This came out of this PR: WideChat/Apps.Salesforce.LiveAgent#85

[ear-dev]

NOTE: this is only an issue with our sf_emulator. We are not seeing this against the Viasat Salesforce instances. We should investigate and fix why this is happening in the emulator, although not a high priority.