Server: v30.0.6rc2 Release

What's Changed

• [stable30] enh: Fix display default expire date, add tests & tiny refactors by @backportbot in https://github.com/nextcloud/server/pull/50694
• [stable30] fix(AccountProperty): better validation of twitter and fediverse handles by @backportbot in https://github.com/nextcloud/server/pull/50699
• [stable30] feat(theming): allow to disable standalone windows by @backportbot in https://github.com/nextcloud/server/pull/50687
• [stable30] chore(deps-dev): bump cypress-split from 1.24.7 to 1.24.9 by @dependabot in https://github.com/nextcloud/server/pull/50726
• [stable30] chore(deps-dev): bump @nextcloud/cypress from 1.0.0-beta.12 to 1.0.0-beta.13 by @dependabot in https://github.com/nextcloud/server/pull/50725
• [stable30] fix(setupcheck): Update setup check for PHP version to be more accurate by @backportbot in https://github.com/nextcloud/server/pull/50750
• 30.0.6 RC2 by @Altahrim in https://github.com/nextcloud/server/pull/50755

Full Changelog: https://github.com/nextcloud/server/compare/v30.0.6rc1...v30.0.6rc2