After a trio of leftists in New York City defeated establishment-backed candidates in congressional primaries, a bouquet of flowers and a sympathy card arrived at the Capitol Hill office of Rep. Hakeem Jeffries of New York, the minority leader. “With heartfelt sympathy,” read the trolling card from the House Republicans’ campaign arm, mocking Jeffries, who had backed two of the losing candidates. Progressives were cheering their victories in New York on Wednesday.