[SMOKECO] - Follow up: Use Event Subscription instead of Attribute Subscription

[jtrejoespinoza-grid]

From: project-chip/connectedhomeip#43654 (comment)

Summary Title:

In the test cases SMOKECO 2.2 and SMOKECO 2.3 use EventSubscription instead of Attribute subscription for SmokeAlarm and COAlarm.

Description:

The cluster support the Events for CoAlarm and SmokeAlarm so there should not be need to use attribute subscription. Update the test script and test plan accordingly.