cli/command/start: delete non-needed tostring() calls
cli/command/start: delete non-needed tostring() calls

The new version of lua-resty-execvp makes sure that tostring() is called
in the envs that it receives via params, so we no longer need to worry
about it.

3scale/apicast,3scale/apicast,3scale/docker-gateway,3scale/apicast,3scale/docker-gateway,3scale/apicast