fix: ensure a spark application can only be submitted once

[razvan]

Description

Fixes #457

Kubernetes recycles Spark applications jobs after ttlSecondsAfterFinished (10min currently) but the application objects live forever (or until the user deletes them).
If a reconciliation is triggered on an app that has no child Job, the operator will submit the Job again.

The fix is to use the application's status field as guard for the reconciliation loop.

I tested it by:

1. running the smoke integration test with --skip-delete
2. After the test finished successfully I deleted the Spark pi Job object
3. I deleted the operator pod (simulated a restart)
4. The Job was not submitted again and in the operator logs I see:

│ 2024-09-12T13:14:51.650689Z  INFO app_controller:reconciling object{object.ref=SparkApplication.v1alpha1.spark.stackable.tech/spark-pi-s3-1.kuttl-test-meet-martin object.reason=object updated}: stackable_spark │
│ _k8s_operator::spark_k8s_controller: Skip reconciling SparkApplication [spark-pi-s3-1] with non empty status  

🟢 CI: https://testing.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/spark-k8s-operator-it-custom/4/

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1. Changes are OpenShift compatible
2. CRD changes approved
3. CRD documentation for all fields, following the style guide.
4. Helm chart can be installed and deployed operator works
5. Integration tests passed (for non trivial changes)
6. Changes need to be "offline" compatible

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1. Code contains useful comments
2. Code contains useful logging statements
3. (Integration-)Test cases added
4. Documentation added or updated. Follows the style guide.
5. Changelog updated
6. Cargo.toml only contains references to git tags (not specific commits or branches)

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[sbernauer]

Functionality LGTM, only some style questions

[sbernauer]

Thanks! Can you please run a Jenkins custom test before merge?

[razvan]

CI https://testing.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/spark-k8s-operator-it-custom/5/

[sbernauer]

Thanks!