feat(catalog): add E2E tests and Kustomize overlay for Python client

[Al-Pragliola]

Description

Adds E2E tests and Kustomize deployment overlay for the Model Catalog Python client.

Depends on: #2065 (Python client PR)

Tests Added (catalog/clients/python/tests/)

File	Coverage
test_sources.py	Source listing, status, paths, merge behavior
test_models.py	Model filtering, pagination, source references
test_artifacts.py	Artifact filtering, ordering, custom properties
test_ordering.py	Name and accuracy ordering (ASC/DESC)
test_filter_options.py	Filter options, named queries validation
test_source_preview.py	Stateless source preview API
fuzz_api/	Schemathesis-based API fuzzing

Kustomize Overlay (manifests/kustomize/options/catalog/overlays/e2e/)

• kustomization.yaml - Overlay extending catalog base
• sources.yaml - Test catalog source configuration
• test-catalog.yaml - Test data (9 models with artifacts)
• disabled-catalog.yaml - Disabled source test data

How Has This Been Tested?

cd catalog/clients/python
# use DOCKER=podman make deploy if using podman instead of docker
make deploy      # Creates a new KinD cluster 
make test-e2e
make deploy-cleanup

Merge criteria:

• All the commits have been signed-off (To pass the DCO check)

• The commits have meaningful messages
• Automated tests are provided as part of the PR for major new functionalities; testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work.
• Code changes follow the kubeflow contribution guidelines.
• For first time contributors: Please reach out to the Reviewers to ensure all tests are being run, ensuring the label ok-to-test has been added to the PR.

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[fege]

already spoke with @Al-Pragliola about this, but I think that we can eliminate the existing fuzz test for the catalog that are https://github.com/opendatahub-io/model-registry/blob/main/clients/python/tests/fuzz_api/model_catalog/test_catalog_stateless.py in favor of this ones