Extract rogue env vars

[dragonchaser]

We have added a little tool that will extract global env vars, that are loaded
only through os.Getenv for documentation purposes

refs #4916

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[mmattel]

When running locally, regarding global_vars.yaml:

• some entries are getting double present like MICRO_LOG_LEVEL (but not only)
  path: ocis-pkg/log/log.go:34
path: ocis-pkg/log/log.go:30
• strange env vars like (rawname):
  parts[0]
registryAddressEnv
• description text
  When adding a description text and re-running make docs-generate, there is no change in global_configvars.adoc

[ownclouders]

💥 Acceptance test localApiTests-apiGraph-ocis failed. Further test are cancelled...

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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