By Ron Bousso and Dmitry Zhdannikov LONDON (Reuters) -BP said on Sunday it plans to abandon its 19.75% stake in oil giant Rosneft in the wake of Russia’s invasion of Ukraine, marking an abrupt and costly end to 30 at times fraught years operating in the oil-rich country. The British oil and gas giant did not say how it planned to exit its stake, which it said would result in charges of up to $25 billion at the end of the first quarter. Rosneft accounts for around half of BP’s oil and gas reserves and a third of its production. “I have been deeply shocked and saddened by the situation unfolding…