Do not check if tag exists + use alpine/helm:3

• Stop checking if the tag already exists as now tags in registry.cern.ch/monit are immutable
  • https://registry.cern.ch/harbor/projects/3717/tag-strategy/immutable-tag
• Use alpine/helm:3 a-la-cloud-native to simplify the CI
• Use registry.cern.ch as entry point directly as:
  • "Harbor only supports the Registry V2 API. You must use Docker client 1.6.0 or higher when pushing and pulling images." https://goharbor.io/docs/1.10/working-with-projects/working-with-images/pulling-pushing-images/

requested review from @bgarrido

approved this merge request

added 14 commits

• 269ca42f...009786dd - 11 commits from branch master
• 8a4c3343 - Stop performing a version existence check
• 40510831 - Use alpine/helm to push the chart to registry.cern.ch
• 36215220 - Use default entrypoint of registry.cern.ch (defaults v2)

Compare with previous version

enabled an automatic merge when all merge checks for 36215220 pass

merged