In Washington, after months of delay and partisan bickering, the Senate voted yesterday to confirm Alexis Herman as labor secretary, filling out the final spot in President Clinton’s second-term Cabinet. The 85-to-13 vote came quickly after the White House agreed to drop plans for a labor-friendly executive order that many GOP senators opposed. The Republicans, led by Oklahoma Senator Don Nickles and backed by business groups, had vowed to block Herman’s nomination indefinitely unless Clinton backed down. The executive order would have required federal agency heads to consider using union-like labor agreements on all federally funded construction projects. Instead, Clinton said, he would issue an executive memorandum on the matter, which, according to White House officials, carries some of the same weight but would expire along with Clinton’s presidency.