[BUG] `npm_command` env not getting set

[isaacs]

At some point in the v7 beta/rc line, we shuffled around the order of when configs are loading and envs are set, and ended up clobbering the npm_command environment variable.

Current Behavior:

{
  "name": "test-command-env",
  "version": "1.0.0",
  "scripts": {
    "test": "echo $npm_command"
  }
}

$ npm test

> test-command-env@1.0.0 test
> echo $npm_command

null

Expected Behavior:

$ npm test

> test-command-env@1.0.0 test
> echo $npm_command

test