WASHINGTON — All but five Senate Republicans voted in favor of an effort to dismiss Donald Trump’s historic second impeachment trial on Tuesday, making clear a conviction of the former president for “incitement of insurrection” after the deadly Capitol siege on Jan. 6 is unlikely. While the Republicans did not succeed in ending the trial before it began, the test vote made clear that Trump still has enormous sway over his party as he becomes the first former president to be tried for impeachment.