Replace Molecule BigBang component placeholder assertions with real tests

User Story:

As a developer, I want real test assertions for BigBang component so that BigBang operator functionality is validated

Problem Statement:

BigBang component tests don't validate PlatformOne BigBang deployment, Helm chart installation, or component dependencies.

Acceptance Criteria:

• BigBang CRD creation validated with correct configuration
• Helm chart deployments verified (Flux, Istio, etc.).
• Component dependency ordering validated
• Platform readiness checks implemented
• GitOps sync status verified
• Values override mechanism tested
• Idempotency verified (no changes on second run)

Implementation Details:

Files to Modify:

• molecule/default/tasks/bigbang_test.yml - Replace placeholder assertions with real tests
• molecule/default/vars/bigbang_test_vars.yml - Test data for BigBang deployment scenarios

Dependencies:

• helm Python library
• kubernetes Python client.
• flux CLI for GitOps validation

Additional Notes:

Validate Flux controllers are running, verify Helm releases are deployed, check Istio service mesh configuration, and ensure all BigBang core components reach ready state.

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