Fix KeyError on optional execute field in recipes_from_tests

[andmat900]

Applicable Issues

Fixes eiffel-community/etos#561

Description of the Change

The execute field in the Environment CRD Execution struct is optional (omitempty), so Kubernetes omits it when the array is empty. recipes_from_tests() used a direct dictionary lookup (test["execution"]["execute"]) which raises a KeyError when the field is absent. This change uses .get("execute", []) instead, returning an empty list as the default.

Alternate Designs

Could have made all execution field lookups defensive with .get(), but only execute is actually optional in the CRD schema, so a targeted fix is more appropriate.

Possible Drawbacks

None expected — this only affects the execute field which is explicitly optional.

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Signed-off-by: Andrei Matveyeu, andreimu@axis.com