[Toybox] Env sh runs toysh instead of system shell

[Denys Nykula]

> enabled toysh in your config
> didn't select "Disable recursive execution"
> I'm not going to special case env.

Both settings are intentional. Had learned that one of common env usages is to
specifically to opt out of shell builtins and force PATH lookup for one
command, like in answers below. Is this wrong? When one wants builtins, they
just set variables before the command name, no?

https://unix.stackexchange.com/questions/103467/what-is-env-command-doing
https://stackoverflow.com/questions/29540540/how-do-i-prevent-bash-to-use-a-builtin-command