Renames "Manage" stage to "Foundations"

data/deprecations/14-3-deprecation_omniauth-kerberos_gem.yml

data/deprecations/14-3-repository-push-audit-events.yml

...vsa-announce-deprecation-of-vsa-filtering-calculation.yml

data/deprecations/14-8-enforce-pat-expiration.yml

data/deprecations/14-8-enforce-ssh-expiration.yml

data/deprecations/14-8-graphql-ids.yml

...cations/15-0-instance-statistics-graphql-node-removal.yml

data/deprecations/15-0-oauth-noexpiry.yml

data/deprecations/15-0-oauth.yml

data/deprecations/15-1-jira-github-enterprise-dvcs.yml

data/deprecations/15-10-omniauth-dingtalk.yml

data/deprecations/15-3-omniauth-cas3.yml

data/deprecations/15-4-non-expiring-access-tokens.yml

data/deprecations/15-7-deprecate-phabricator-importer.yml

data/deprecations/15-7-deprecate-shimo-integration.yml

data/deprecations/15-7-deprecate-zentao-integration.yml

data/deprecations/15-7-remove-flowdock-integration.yml

...ecations/15-8-deprecate-deploy-PAT-with-external-auth.yml

data/deprecations/15-8-deprecate-gitlabcom-importer.yml

...ons/15-8-deprecate-import-bare-repositories-rake-task.yml