Add more functionality coverage to k8s_rollback integration test (#950)

SUMMARY

Resolves #344

This revision adds the following test coverage:

Label Selectors: Tests rollback using label selectors to target specific deployments.
No Rollout History: Tests the warning scenario when attempting to rollback a deployment with only one revision.
Unsupported Resource Types: Tests error handling when trying to rollback unsupported resources like Services.
Non-existent Resources: Tests behavior when attempting to rollback resources that don't exist.
Multiple Resource Rollback: Tests bulk rollback operations using label selectors on multiple deployments.
Return Value Validation: Comprehensive validation of the rollback_info structure and content.
Field Selectors: Tests rollback using field selectors to target specific resources.
Check Mode Validation: Additional validation of check mode behavior and return values.

COMPONENT NAME

tests/integration/targets/k8s_rollback/tasks/main.yml

Reviewed-by: Alina Buzachis
Reviewed-by: Bikouo Aubin
Reviewed-by: Bianca Henderson <beeankha@gmail.com>

changelogs/fragments/20250704-k8s-rollback-integration-test-coverage.yaml

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+trivial:
+  - k8s_rollback - Increase integration test coverage for k8s_rollback module (https://github.com/ansible-collections/kubernetes.core/pull/950).