I'm afraid you already know the answer - it has to come out! I am not a plumber, just a few years ahead of you in experience.
It's just as likely that the copper has corroded from the inside, not from the effects of the concrete. If it is internal corrosion you can expect another pin-hole to appear before long. I've heard and read stories of cheap Chinese copper being at fault - recycled copper, inclusions in the metal etc. - starting from around 20 years ago, but who knows? We are on soft, spring water and (some) copper simply doesn't last with us. I had to replace our incoming cold main as it sprung a leak 2 foot below a concrete floor which was seeping from the external wall. It's not buried now!
Copper should always be protected in concrete - Denso tape, plastic coating, ducting, foamed insulation - whatever separates the two and preferably allows for expansion. It's common sense that everything should be ducted and accessible - it's so easy in a new floor but a nightmare in an existing floor. I am currently looking at channelling about 2m of hot and cold pipes in a concrete floor (to save about 12m of convoluted pipe run) - it will be 15mm plastic pipe threaded through 22mm pipe with no hidden joints.
We're having some work done soon and part of that will involve replacing all copper water pipes with plastic. And no pipework in the loft! A ground floor leak is bad enough but ceilings coming down is worse. All our heating pipes are already plastic but also buried in concrete and there must be at least 12 joints buried in there- I have a feeling that eventually the carpets will be coming up there too, but it's lasted 28 years without any problems.
Wow, your problem is easily fixed but it's the disruption and expense that seems daunting, I know. Bloody concrete floors!