Draft: fix truth match and add track cov
1.fix truth match according to Luke Grazette's advice: lhcb/Moore#821
2.add track covariance variables following Mengzhen’s merged request: !1638 (merged)
1.fix truth match according to Luke Grazette's advice: lhcb/Moore#821
2.add track covariance variables following Mengzhen’s merged request: !1638 (merged)