Update CHANGELOG.md for 11.7.0

CHANGELOG.md

changelogs/unreleased/18667-handle-push-opts.yml

changelogs/unreleased/23367-clarify-docs-allow-failure.yml

...27861-add-markdown-editing-buttons-to-the-file-editor.yml

...d/29951-issue-creation-by-email-without-subaddressing.yml

...logs/unreleased/34758-extend-can-create-cluster-logic.yml

changelogs/unreleased/34758-list-ancestor-clusters.yml

...gs/unreleased/40270-remove-gitlab-upgrader-completely.yml

...released/40473-api-support-for-kubernetes-integration.yml

changelogs/unreleased/41766-vue-component.yml

changelogs/unreleased/41766-vuex-store.yml

...eased/42125-extend-override-check-to-also-check-arity.yml

...ed/43623-add-submit-feedback-in-product-feedback-link.yml

...s/unreleased/44353-improve-snippet-search-performance.yml

.../unreleased/44984-use-serializer-for-issuable-sidebar.yml

...d/47052-merge-button-does-not-appear-after-rebase-ing.yml

...ations-with-secrets-that-aren-t-committed-to-the-repo.yml

changelogs/unreleased/49231-import-issues-csv.yml

changelogs/unreleased/51485-new-issue-labels-note.yml

...n-comment-form-will-always-scroll-down-to-the-comment.yml