BF-46591: Evergreen's `bazel run` wrapper selected `--config=local` when remote execution was disabled or unsupported. That also disabled EngFlow's asset downloader, remote cache, and TLS credentials, exposing repository fetches to GitHub 504s.

Change `compute_local_arg()` in `evergreen/bazel_evergreen_shutils.sh` to select `--config=no-remote-exec`, preserving EngFlow access while running locally. Update the shell regression tests for both execution modes.