Redact sensitive env vars when printing cmd errors. (#61287)
Before:
```
julia +nightly -e 'run(setenv(`false`, "API_KEY" => "hunter2"))'
ERROR: failed process: Process(setenv(`false`,["API_KEY=hunter2"]), ProcessExited(1)) [1]
```
After:
```
julia +dev -e 'run(setenv(`false`, "API_KEY" => "hunter2"))'
ERROR: failed process: Process(setenv(`false`,["API_KEY"]), ProcessExited(1)) [1]
```
