improve gitlab-runner repository/image values in chart
Description
Currently the way to override the image location for the gitlab-runner
image in the chart is to override both the repository and the tag due to the logic in the template defined here: https://gitlab.com/charts/gitlab-runner/blob/master/templates/_helpers.tpl#L61 This doesn't follow the standard way charts define images, which usually looks like this:
image:
repository: alpine
tag: 3.8
pullPolicy: IfNotPresent
Proposal
Use the more generally accepted way of defining the container image by breaking the repository and tag into separate values, so that the repository can be overridden but the tag does not have to. The primary use case for this is on an airgapped network where all I want to do is change the repository location, but not deviate from the version of the image in the chart. This would reduce errors when upgrading by not having to ensure the version is updated in my overrides, as it would stick to the default value in the chart.
The primary GitLab chart uses this approach already, as seen in these examples: