UK Prime Minister Boris Johnson faces two high-stakes encounters in parliament on Wednesday after his government was rocked by the shock departures of two senior ministers. Rishi Sunak resigned as finance minister and Sajid Javid as health secretary on Tuesday night. Both said they could no longer tolerate the culture of scandal that has stalked Johnson for months. They will now sit on the Conservative back benches at the weekly session of Prime Minister’s Questions in the House of Commons at 1100 GMT — which promises to be even more combustible than usual. Johnson then faces an hours-long gr…