Will storing salted steak overnight ruin the meat?

It's quite possible that meat might even be improved. From an article at Serious Eats :

Indeed, the absolute best steak I had was one that I had salted on both sides then allowed to rest on a rack overnight in the refrigerator uncovered. It appears to dry out slightly, but it's only superficial—the amount of drying that occurs from an overnight rest (about 5% moisture loss) is negligible compared to the amount of moisture driven off during cooking anyway (upwards of 20%, even more in the hard-seared edges). As the salt makes its way back into the meat, you'll probably also notice that it becomes a deeper color. That's because the dissolved proteins scatter light differently than they did when they were still whole.

The 'uncovered' is important in the discussion of 'dry brining', as you want the surface to dry out without needing to blot it (which would remove salt with it) ... it doesn't have to be completely uncovered, but whatever cover it has should allow sufficient air flow for it to dry out.

You weren't intending on removing any salt while cooking immediately, so the amount you have salted should be enough for eating it now or later.

If you're worried about being too heavy handed with the salt, you could always rinse it off and then wrap it in paper towels to dry in the fridge overnight. Or wipe it off with a paper towel.

Accurate salting overnight (not too much) should result in a better sear, as the salt draws the moisture out of the meat.