JOHANNESBURG, South Africa — To most South Africans, it is an unimaginable expense: $28 million in upgrades to President Jacob Zuma’s rural homestead, with taxpayers footing the bill. But while the president maintains these upgrades are required for security reasons, this has failed to quell South African outrage over the high cost of the project, along with further revelations that tens of millions more in state funding has been spent on roads in the area.