Improve the copy in the 'Default artifact expiration' section in the instance-level settings

Problem statement

The copy and the help text in the 'Default artifact expiration' section on the Admin area >> CI/CD settings page does not provide with a very clear instruction on how to format the value to be entered and also does not clearly define the scope of the configuration.

Image

Proposal

In a comment on the design here, @marcel.amirault proposed the following change to the copy (drop the s and add time to the title, and improve the detail text):

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• Default artifact expiration time

  Set the default expiration time for job artifacts in all projects. Set to 0 to never expire artifacts by default. If no unit is written, it defaults to seconds. For example, these are all equivalent: 3600, 60 minutes, one hour.