The cash-strapped MBTA is spending $1.2 million on just four independent contractors to manage some of its major initiatives, including quietly signing a labor negotiator away from the Baker administration this past spring to a $100,000 pay bump, a Herald review found.The contracts highlight the T’s increasingly frequent strategy of turning to outside help to manage delay-plagued projects or critical negotiations, often making the so-called “independent contractors” some of the highest paid people working for the T.