env: -v / -vv don't trace environment changes

GNU traces each change; we print nothing for -v, and an unrelated argument dump for -vv.

Ours
```
$ LANG=C ./target/debug/coreutils env -i -v A=1
A=1
```

```
$ LANG=C ./target/debug/coreutils env -i -vv A=1
input args:
arg[0]: 'env'
arg[1]: '-i'
arg[2]: '-vv'
arg[3]: 'A=1'
A=1
```  

GNU 9.11.130 (identical for -v and -vv)
```
$ LANG=C env -i -v A=1
cleaning environ
setenv:   A=1
A=1
```