The last generation was pushing 12 hours on some of my computers. I assume that if you pay for a top-of-the-line server, you can get one of these done in 4-6 hours or so.
I'd honestly think that if you just want to throw money at it, those absurdly-overclocked gamer rigs that can hit sustained +5GHz boosting on just a few cores would be better if you want the fastest P&R times? Cloud servers will probably have more RAM and memory bandwidth but you can shove 128GB of RAM in the 13900K, memory requirements are relatively easy to meet IMO. Synthesis can definitely scale with some more cores in Vivado (OOC synth) but P&R never seemed to scale beyond what you can just get in a desktop. YMMV I guess.
Is it possible to upload just a small bugfix to bitstream?
If you want to upload a small bugfix without it taking 10+ hours, you need to floorplan your design and use "partial reconfiguration" techniques in order to change only part of the bitstream at a time. This requires a more advanced design flow and a bit more work, but is necessary for things like multi-tenancy or lowering turnaround times.