Merge i18n translations (September 2021)

Merge the latest i18n translations from Crowdin on a monthly cadence.

Documentation available here: https://docs.gitlab.com/ee/development/i18n/merging_translations.html

ToDo

• If needed, configure the GitLab-Crowdin integration
• Kick off an import from Crowdin (after September 1)
• Find the MR created by @gitlab-crowdin-bot and associate it with this issue
• Complete the MR
• Update the translation levels data with the latest numbers. #338520 (closed)
• When done, clone this issue for the next milestone.