Tweak bug ID prompting in gnus-group--read-bug-ids

* lisp/gnus/gnus-group.el (gnus-group--read-bug-ids): Default to
current bug id on RET.
Status Job ID Name Coverage
  Test
failed #2561
test-all

 
Name Stage Failure
failed
test-all Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job trace