Update CHANGELOG.md for 13.0.0

CHANGELOG.md

...nreleased/10343-remove-a-lonely-dot-in-batch-comments.yml

...gs/unreleased/118609-design-comment-edit-comment-text.yml

...logs/unreleased/14108-instance-level-ci-variables-api.yml

...released/14108-instance-level-ci-variables-controller.yml

...gs/unreleased/14108-instance-level-ci-variables-logic.yml

changelogs/unreleased/14108-instance-level-ci-variables.yml

...elogs/unreleased/1600-remove-jenkinsdeprecatedservice.yml

...released/195887-jira-comment-details-column-migration.yml

...eased/195887-jira-comment-details-include-branch-name.yml

...rations-list-views-should-use-recommended-page-layout.yml

changelogs/unreleased/196862-drop-plan-id.yml

...nreleased/197170-issues-api-endpoint-missmatch-web-ui.yml

changelogs/unreleased/197344-use-cookies-with-metadata.yml

changelogs/unreleased/198324-avoid_subqueries.yml

...ey-on-projects-namespace-id-and-clean-up-ghost-projec.yml

...-text-for-future-release-date-grammatically-incorrect.yml

...logs/unreleased/199053-inconsistent-help-icon-styling.yml

...in-left-side-navigation-for-the-package-area-to-bette.yml

changelogs/unreleased/199843-fix-viewing-nil-blobs.yml