Fix qlkube schema generation

[QcFe]

Description

This PR removes lines with just an underscore from qlkube generated schema (hopefully enums with empty values that are generated weirdly and break graphql codegen).

[QcFe]

/deploy-staging

[kingmakerbot]

Hi @QcFe. Thanks for your PR.

I am @kingmakerbot.
You can interact with me issuing a slash command in the first line of a comment.
Currently, I understand the following commands:

• /rebase: Rebase this PR onto the master branch
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• /deploy-staging: Deploy a staging environment to test this PR (the build-all flag enables user environments building)
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Make sure this PR appears in the CrownLabs changelog, adding one of the following labels:

• kind/breaking: 💥 Breaking Change
• kind/feature: 🚀 New Feature
• kind/bug: 🐛 Bug Fix
• kind/cleanup: 🧹 Code Refactoring
• kind/docs: 📝 Documentation

[kingmakerbot]

Your staging environment has been correctly deployed/updated!
Available here: Frontend, Qlkube
Operators: add the crownlabs.polito.it/operator-selector=staging-904 label to your tenant.

[QcFe]

/deploy-staging

[kingmakerbot]

Your staging environment has been correctly deployed/updated!
Available here: Frontend, Qlkube
Operators: add the crownlabs.polito.it/operator-selector=staging-904 label to your tenant.

[QcFe]

/merge

[kingmakerbot]

Your staging environment has been correctly teared-down!