Make sure that when a pull request is merged the corresponding issue is closed

[psss]

Config for automated closing has been merged, looks good. There seems to be a problem on sync2jira side:

• Jira issue not closed for merged pull requests release-engineering/Sync2Jira#437

[psss]

The sync2jira issue seems to be fixed. Verified on the recent pull requests:

• Phases added dynamically to a step are added to its queue too #4750
• Clear the library cache when re-running a tmt try #4759
• List packages from repository providers in artifacts.yaml #4703
• Expose step-level queue of phases #4729

However, some new duplicated issues have been discovered during this. Filed as #4778.