In SERVER-33513 I added a "compile_proxy" task in system_perf.yml as a layer of indirection. This was a workaround due to not being able to use depends_on on a variant level. That has now been implemented in EVG-2923. We should therefore use that instead.

Note: While the compile_proxy task is only used for master, the end result of this ticket should also be backported to stable branches, so that system_perf.yml is as consistent as possible across the branches.