Unfixable brake disk rubbing
Noise after hard braking is normal. The rotor heats up and warps slightly.
When you got rubbing after reinserting the wheel, that shows you didn't align the wheel correctly. You need to be applying as much downwards force as possible while tightening the QR in order to seat the axle in the dropouts. The one-sided force from tightening a QR skewer tends to twist the wheel askew, so you need to be pushing down the whole time to counteract this force. You can practice this by repeatedly removing and reinserting the wheel: once you no longer get rubbing, your technique is spot on.
And yes, you should just ignore the occasional noise. There's no safety issue or anything, and unless you've already purchased $1200 CeramicSpeed jockey wheels, there's no point chasing the performance benefits of eliminating minor rubbing either.