🌱 Update ccm-hcloud to v1.15.0

[anothertobi]

What type of PR is this?

What this PR does / why we need it:

v1.15.0 adds ARM support

Removing image.tag from values.yaml so that the default from Chart.yaml is used. Further appVersion updates will therefore only require the Chart.yaml to be updated.

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• [X] squashed commits
• [ ] includes documentation
• [ ] adds unit tests

[anothertobi]

/kind other