Seven Republican presidential candidates bickered about the economy, energy, China and each other’s past policy stances in the second 2024 primary debate Wednesday night, trying to find an opening to challenge the missing frontrunner, Donald Duck — er, former President Donald Trump. “We’re not getting a mulligan on the 2024 election,” Florida Gov. Ron DeSantis said at one point, proposing that a successful GOP ticket would focus on fixing the economy, securing the border and focusing on the growing “threat from China.” But Trump, 77, remained the elephant not in the room for the candidates, a fact driven home by…