Fix some apollo cache issues moving between pages

...ts/javascripts/iterations/components/iteration_report.vue

...ts/javascripts/iterations/queries/iteration.query.graphql

...cripts/iterations/queries/iteration_cadence.query.graphql

...scripts/iterations/queries/iteration_issues.query.graphql

.../queries/iteration_issues_with_label_filter.query.graphql

...s/javascripts/iterations/queries/iterations.query.graphql

...tend/iterations/components/iteration_cadence_form_spec.js

...pec/frontend/iterations/components/iteration_form_spec.js

...end/iterations/components/iteration_report_issues_spec.js

...c/frontend/iterations/components/iteration_report_spec.js

ee/spec/frontend/iterations/mock_data.js