Align Stackable conditions with K8s conditions

[sbernauer]

While trying to parse our status.conditions list as Vec<Condition> serde_json complained about the field lastTransitionTime not being present (in case the Trino cluster is stopped). This is because we have our hand-crafted version of a Condition here

Ideally we should use the k8s-openapi Conditions struct internally, similar to

pub struct ClusterCondition {
    #[serde(flatten)]
    pub condition: Condition,

    /// The last time this condition was updated.
    pub last_update_time: Time,
}