An MTA employee was stabbed on a subway platform in the Bronx on Thursday morning in the latest violent incident on the city’s troubled transit system, police and sources said.The 47-year-old worker was cleaning the Pelham Parkway Station around 6:10 a.m.when an unidentified man stabbed him in the armpit following a verbal dispute, according to police and sources.The victim was rushed to Jacobi hospital in stable condition, cops said.The attacker, described as a man in his 50s or 60s in a black hoodie and black pants, fled the station to parts unknown, police said....