Fix twoClustersTunnel flakiness

[tobiaszheller]

This PR fixes: #26225.

Before stopping auth, we make sure that 2nd event is received.

This test was flaky before but I believe it gotten worse after explicitly closing log on process stop (

teleport/lib/auth/auth.go

Lines 1191 to 1195 in e9d397e

	if a.Services.AuditLogSessionStreamer != nil {
	if err := a.Services.AuditLogSessionStreamer.Close(); err != nil {
	errs = append(errs, err)
	}
	}

).

Node is using async emitter and if we stop auth immediately after sending exec, there is high chance that it won't be there. Adding explicit close on events log, cause it to fail more often because it's closed earlier.

[zmb3]

nice!

[public-teleport-github-review-bot]

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