[CI] `staging_release` job does not update appVersion in Chart.yaml files

Summary

The staging_release job packages the Helm chart without first modifying the Chart.yaml files with the specific appVersion (using scripts/manage_version.rb).

This means that when the Helm chart is downloaded, appVersion: master. Therefore, the Deployments will pull images at the tag master rather than at the specific version for which the Chart was packaged.

Steps to reproduce

1. Replicate steps from staging_release job:
   1. helm dependency update
   2. helm package .
2. Extract the package to validate the content of appVersion:
   1. mkdir gitlab-packaged
   2. tar -xf gitlab-5.4.1.tgz -C gitlab-packaged/
   3. grep 'appVersion' gitlab-official/gitlab/Chart.yaml -> appVersion: master
3. Compare the results to an officially release Helm chart
   1. rm gitlab-5.4.1.tgz
   2. mkdir gitlab-official
   3. helm pull gitlab/gitlab --version 5.4.1
   4. mkdir gitlab-official
   5. tar -xf gitlab-5.4.1.tgz -C gitlab-official/
   6. grep 'appVersion' gitlab-official/gitlab/Chart.yaml -> appVersion: 14.4.1

Current behavior

Downloading a chart from the staging_release output specifies appVersion: master in the Chart.yaml files.

Expected behavior

Downloading a chart from the staging_release output specifies appVersion: <version> in the Chart.yaml files, where version is something like 14.4.1.