Where do mined bitcoins go?
Bitcoin Core no longer contains any mining code, so it's definitely not mining.  (If it were, you'd see 100% CPU usage.)  Mining has nothing to do with the behavior you are seeing.

You're downloading the entire block chain (150+ GB) and checking it for validity, which explains the CPU usage.   The UpdateTip message simply records that you've received a new block, and you've checked it and determined that it is a valid addition to the blockchain.  This is normal behavior for Bitcoin Core or any other full node, and is inherent to its operation.

I see you have enabled pruning, so that will save disk space.  It won't save bandwidth or CPU though.  If you don't want to use that much bandwidth, don't use Bitcoin Core.  There are other "thin" wallet clients that don't need to download the entire blockchain - the tradeoff is that you have to trust other nodes to tell you that transactions are valid, instead of being able to check it for yourself.