Superconductivity is a very different thing and very weird (Cooper pairs, BCS thoery, Nobel Prize stuff). It has a very sudden onset.
Cold can often drop resistance in metals but the conduction mechanism is different there from that in electrolytes - conduction band electrons are essentially ‘delocalised’ i.e. not bound to the metal’s crystal lattice and the only thing which resists their motion is scattering off things like crystal defects and phonons. Phonons are lattice vibrations which act as quasi-particles (no I can’t really remember either, but it’s all in Ashcroft and Mermin). At lower temperatures there are fewer phonons so electrons in metals meet less resistance.