The 'ready user story point' metric doesn't necessarily measure ready user stories only, so drop the 'ready'

[fniessink]

The user is responsible for supplying a JQL (Jira) or WIQL (Azure DevOps) query that Quality-time uses to get the user stories from the source. So it's up to the user to decide which user stories to include. The user could just as wel use this metric to count the points of e.g. completed user stories or user stories in the current sprint.

Tasks:

• Rename the key of the metric to user_story_points in the data model
• Change the name of the metric to "User story points" and update the description
• Add both user_story_points to the Quality-time source, and keep ready_user_story_points so Quality-time can measure old versions of itself.
• Add a GitHub issue to remove the ready_user_story_points metric from the Quality-time source on the next major version: see Code to remove on the next major version of Quality-time #1416
• Migrate the reports on startup of the server
  • To use the new key
  • For metrics that use the old default name "Ready user story points" add a custom name "Ready user story points" to prevent the name from changing to "User story points"