Xcode CAS daemon honors the private cache endpoint on runners

On Tuist Cloud runners, the private-network cache endpoint the runner dispatches is now also forwarded to the Xcode compilation cache (CAS) daemon’s launchd environment, not just the binary module cache. Before this, the module cache hit the private node and the CAS resolved through the public endpoint via getCacheEndpoints, so on a full compile the Xcode cache was net-negative. The kura feature-flag forwarding from #11481 alone was not enough because getCacheEndpoints deliberately returns the public, CLI-facing endpoint.