Enterprise Traffic Graph: Ensure license data is visible on Cloud

[gally47]

On Cloud we display initially the traffic until max daily value (so that it's visible), then we can click Zoom/Reset to see the traffic limit line.

Motivation and Context

fixes https://github.com/Graylog2/graylog-plugin-enterprise/issues/6055

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.