delete the readme of performance regression test (#5359)
delete the readme of performance regression test (#5359)

delete the readme of performance regression test
intel-analytics/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL