OZG-3328 set imagePullSecret as required and cleanup

src/main/helm/templates/_helpers.tpl

src/main/helm/templates/deployment.yaml

src/main/helm/templates/image_pull_secret.yaml

src/test/helm-linter-values.yaml

src/test/helm/deployment_63_chars_test.yaml

src/test/helm/deployment_bindings_test.yaml

...test/helm/deployment_container_security_context_test.yaml

...test/helm/deployment_defaults_containers_health_test.yaml

src/test/helm/deployment_defaults_labels_test.yaml

src/test/helm/deployment_defaults_spec_containers_test.yaml

...m/deployment_defaults_topologySpreadConstraints_test.yaml

src/test/helm/deployment_env_customList_test.yaml

src/test/helm/deployment_host_aliases_test.yaml

src/test/helm/deployment_imagepull_secret_test.yaml

src/test/helm/deployment_liveness_probe_test.yaml

src/test/helm/deployment_pod_default_spec_values_test.yaml

src/test/helm/deployment_resources_test.yaml

src/test/helm/deployment_routing_strategy_env.yaml

src/test/helm/deployment_service_account_test.yaml

src/test/helm/deployment_springProfile_env_test.yaml