Show test reports immediately on pipeline tests tab

What does this MR do and why?

This is step 2 of #369944 (closed).

Now we add back the Ci::Pipeline#has_reports? method without the pipeline complete? check. This will now be used by the pipeline test report endpoint and eventually other reports that don't have to wait for pipeline completion to be generated.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.