Avoid retrieval of tenant namespace by name

[fra98]

Description

This PR refactors some liqoctl commands to not rely on the metadata name to retrieve a tenant namespace. Retrieval by naming is unsafe as tenant namespace names can be customized and one should rely only on labels to retrieve the correct tenant namespace.

The PR makes the function that generates the default tenant namespace name private and modifies liqoctl commands to only rely on the NamespaceManager interface to retrieve the correct namespace.

[adamjensenbot]

Hi @fra98. Thanks for your PR!

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Make sure this PR appears in the liqo changelog, adding one of the following labels:

• kind/breaking: 💥 Breaking Change
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[fra98]

/test

[fra98]

/test

[fra98]

/rebase test=true

[fra98]

/merge