Remove IsEnabled from Write in DiagnosticSourceAdapter

[jbagga]

The Write method in the DiagnosticSourceAdapter calls InEnabled which needs to be removed.
https://github.com/aspnet/EventNotification/blob/dev/src/Microsoft.Extensions.DiagnosticAdapter/DiagnosticSourceAdapter.cs#L82-L85

See comment #65 (comment)
See PR: #65

cc @Eilon @rynowak

[Eilon]

Close?

[jbagga]

Yeah was just waiting for it to pass on the CI