The driver system isn't bypassed. By removing the jumper, you separated(isolated) the logic side of the module from the power side of the module. That is the way it 'should' be done. The logic side doesn't use much current at all, and can be sourced from the digital I/O pins without issue. The current to energize the relay is now isolated from the arduino and is getting it's power from the 7805, which has it's limits too. It will get hot as well if you pull to much power through it