Fix loki gateway url when deployed on non-dev namespace

[aktech]

Reference Issues or PRs

It was accidentally assumed that Nebari will always be deployed on "dev" namespace, hence the constructed loki gateway url was not correct for non dev namespaces. This PR makes sure to incorporate namespace in gateway url.

What does this implement/fix?

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features not to work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

• Did you test the pull request locally?
• Did you add new tests?

Any other comments?