Whole Foods, the grocery chain possessed by Amazon.com Inc., is cutting health advantages as far as it matters for its part-time laborers in a move that could leave around 1,900 of them without medical coverage. Beginning one year from now, Whole Foods employees need to work in any event 30 hours per week to meet all requirements for company health insurance benefits, up from the 20 hours seven days at present required. The upscale grocer, which has around 95,000 workers,