Add test regression index for list of test plan runs
Add test regression index for list of test plan runs

Add a new test regression index to be used when retrieving all the
runs of a given test plan, on a platform with a kernel revision.

Signed-off-by: Guillaume Tucker <e7e20b7c30f19d4ca6b81319ef81bf200369d137@collabora.com>

kernelci/kernelci-backend,kernelci/kernelci-backend