Preserve existing metadata labels (and other fields) in SparkApplication manifest

[mohamed-mis]

This PR addresses an issue in the CustomObjectLauncher operator within the Kubernetes provider, where submitting a SparkApplication manifest -using the SparkKubernetesOperator- results in the loss of existing metadata labels and annotations.

The current implementation in get_body() overwrites the entire metadata object:
self.body.metadata = {"name": self.name, "namespace": self.namespace}
This discards any pre-existing metadata such as labels, annotations, or custom fields.
This PR replaces the overwrite with an in-place update using dict.update().

Testing:
This fix has been validated with the following setup:

• Airflow Version: 3.0.6
• Deployment Method: Official Helm chart 1.18.0
• Kubernetes Provider Version: apache-airflow-providers-cncf-kubernetes==10.7.0
• Python Version: 3.12.11

SparkApplication resources submitted via the SparkKubernetesOperator now retain their original metadata labels as expected.

---

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[boring-cyborg]

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[mohamed-mis]

All GHA checks were successful, except for [CI image checks / Static checks], which failed due missing licence text in other files not related to the PR.

[nevcohen]

Looks good! Just add test

[mohamed-mis]

tests for the custom_object_launcher already exist and covers the updated part.
test_custom_object_launcher.py

[eladkal]

tests for the custom_object_launcher already exist and covers the updated part.

Your PR changes/fix behavior thus you can't claim tests already cover the fix.
You don't have to write a new test, it could be that extend or fix to a current test is enough. The idea is that the change you are implemented here won't be regressed in future versions so the way to make sure it doesn't happen is with test coverage.

[mohamed-mis]

Tests added:

• test_get_body_initializes_metadata_when_missing
• test_get_body_replaces_non_dict_metadata
• test_get_body_preserves_existing_metadata_labels

Waiting for GHA to finish all workflows, otherwise it should be good (fingers Crossed).

[nevcohen]

Now it's ready. It looks great!

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.