Fix panic due to early onEvent Logger call in Zookeeper event handling

[ytake]

This commit removes the Logger call from the onEvent method in the Zookeeper event handling code.
Previously, invoking p.cluster.Logger() before the cluster was fully resolved led to a runtime panic error (panic: runtime error: invalid memory address or nil pointer dereference).

This change is a workaround to avoid the immediate crash.

I think you need to refactor the initialization sequence of the "provider" and its dependencies to ensure that the "cluster" is available before any event processing takes place.

[CLAassistant]

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