feat(deployment): add image.repository as alias for image.image

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What does this MR do?

add image.repository as possible value alias for image.image

Why was this MR needed?

tools like RenovateBot rely on common conventions to detect used software. charts commonly allow users to customize the image name/repository using image.repository as values input. currently custom configuration needs to be deployed in order to detect the gitlab-runner image as potential software dependency.

What's the best way to test this MR?

unit test have been added to verify the change and backwards compatibility support. manual test can be performed by rendering the chart with a custom image.repository value.

What are the relevant issue numbers?

n/a