Fix: modify the logic error of EventChangedType in EtcdRepository.java

[AsyncKurisu]

Fixes #33134

Problem Description:
The incorrect event type determined in getEventChangedType() is propagated into the DataChangedEvent object. Since subsequent metadata refresh logic relies entirely on event.getType(), the misclassified type leads to incorrect execution paths in both onChange() and handle(). As a result, a DELETE event may be processed as an ADD event, preventing the expected metadata removal and causing metadata refresh inconsistencies.

Changes proposed in this pull request:

• modify the logic for checking when version=1 in getEventChangedType in EtcdRepository.java
• add test functions for verifying the correctness of the WatchEvent.EventType

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[AsyncKurisu]

@terrymanu Can you please review this pr?