Draft: Fix broken links

From https://codebase.helmholtz.cloud/hifis/overall/hifis.net/-/jobs/2014745:

• At public/consulting-handbook/publication_policy/index.html:434:
  External link https://www.dfg.de/download/pdf/foerderung/rechtliche_rahmenbedingungen/gute_wissenschaftliche_praxis/kodex_gwp_en.pdf failed (status code 404)
• At public/consulting-handbook/publication_policy/index.html:498:
  External link https://www.dfg.de/download/pdf/foerderung/rechtliche_rahmenbedingungen/gute_wissenschaftliche_praxis/kodex_gwp_en.pdf failed (status code 404)
• At public/consulting-handbook/publication_policy/index.html:503:
  External link https://www.dfg.de/download/pdf/foerderung/rechtliche_rahmenbedingungen/gute_wissenschaftliche_praxis/kodex_gwp_en.pdf failed (status code 404)
• At public/documentation.html:578:
  External link https://hifis.net/doc/service-portfolio/service-portfolio-management/current-services-in-portfolio/ failed (status code 404)
• At public/milestone/2021/11/17/CloudPortal.html:684:
  External link https://hifis.net/doc/service-portfolio/service-portfolio-management/current-services-in-portfolio/ failed (status code 404)
• At public/news/2020/03/13/jsc-hpc-support-for-covid-19-research.html:634:
  External link https://www.fz-juelich.de/SharedDocs/Meldungen/IAS/JSC/EN/2020/offer-covid-19.html failed (status code 404)
• At public/news/2022/03/31/service-portfolio-review.html:755:
  External link https://hifis.net/doc/service-portfolio/service-portfolio-management/current-services-in-portfolio/ failed (status code 404)
• At public/news/2022/05/05/service-canvas-now-available-in-Plony.html:718:
  External link https://hifis.net/doc/service-portfolio/service-portfolio-management/current-services-in-portfolio/ failed (status code 404)
• At public/news/2022/05/10/HI-Contest.html:696:
  External link https://awards.helmholtz-imaging.de/entry/vote/lgpGbmxR failed: Not Found (status code 404)
• At public/news/2022/12/12/evaluation-update.html:739:
  External link https://syncnshare.desy.de/index.php/f/467281196 failed: Unauthorized (status code 401)
• At public/news/2023/10/16/IT4science.html:791:
  External link https://www.mdc-berlin.de/de/forschung/infrastruktur/kongresszentrum failed (status code 406)
• At public/news/2024/02/02/hfmi.html:731:
  External link https://events.hifis.net/e/matchmakingHFMI failed: Bad Request (status code 400)
• At public/publications.html:663:
  External link https://www.helmholtz-berlin.de/media/media/oea/aktuell/print//lichtblick/246/hzb_lichtblick_ag-44_september-2020_extern_web.pdf failed: Not Found (status code 404)
• At public/publications.html:686:
  External link https://betterscientificsoftware.github.io/swe-cse-bof/2019-11-sc19-bof/04-haupt-helmholtz.pdf failed (status code 404)
• At public/services/cloud/provider.html:664:
  External link https://hifis.net/doc/software/ failed (status code 404)
• At public/services/overall/itsupport_benefit.html:647:
  External link https://hifis.net/doc/service-portfolio/service-portfolio-management/current-services-in-portfolio/ failed (status code 404)
• At public/tutorial/2019/11/22/How-to-Create-a-new-Blog-Post.html:871:
  External link https://docs.gitlab.com/ce/ci/introduction/index.html failed (status code 404)
• At public/tutorial/2019/11/22/How-to-Create-a-new-Blog-Post.html:919:
  External link https://docs.gitlab.com/ce/ci/introduction/index.html failed (status code 404)