[BUG] ScaleIn Instance without specifying lifeCycleActions causing panic

[ian-hui]

Describe the Bug

Background:

1. I used opsRequest to scale in a component by specifying an instance to offline using OnlineToOfflineInstance.
2. I did not specify any lifecycle in the componentDefinition.

Problem:
A nil pointer panic occurred, causing Kubeblocks to enter a crashLoop.

the code which causing panic

Note: In the trace path, it appears that a lifecycle action was triggered by kbagent, but as illustrated above, I did not specify any lifecycle in the componentDefinition.

[shanshanying]

@leon-inf PTAL