feat: Add check for event.Series.LastObservedTime

[NachoxMacho]

Brief description of Pull Request

This updates the event timestamp check, to utilize the series.lastObservedTime field if present, and default to existing logic if it's not present. Adds an if statement to the event timestamp function for this check.

Pull Request Details

The existing timestamp logic has an issue when an event doesn't get a lastTimestamp and only has eventTime and series.lastObservedTime. This causes events that are valid, but repeat using the series functionality to only be registered when they were initially created, making the timestamping inaccurate.

This seems to be currently isolated to the scheduler's event reporting node availability when a pod can't be scheduled. For example:

0/16 nodes are available: persistentvolumeclaim "pvc-redisinsight" not found. not found

I have not seen any instances in my investigation where both lastTimestamp and series.lastObservedTime are defined, however in this case I think it would be beneficial to use the series.lastObservedTime as that is the newer of the two fields.

This also seems to be the general direction of the Kubernetes event structure going forward, with lastTimestamp being deprecated in 1.25, so I'd expect this problem to ripple out to other events as more get updated.

Issue(s) fixed by this Pull Request

Fixes #206
Fixes #4140

Notes to the Reviewer

This is my first PR to the repository, so let me know if I've missed anything or this is an incorrect way to suggest a change. I have written all the content of the change and this PR description myself, and not used AI for any of the work related to this.

PR Checklist

• Documentation added
• Tests updated
• Config converters updated
• This pull request was substantially generated with AI assistance (see the GenAI policy)

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