bug [test] target: environment should ignore other environment specific tests

**Describe the bug**
The test runner produces the following pattern for testing:

```sh
[
'test/.{js,cjs,mjs}',
'test/**/*.spec.{js,cjs,mjs}',
'dist/test/.{js,cjs,mjs}',
'dist/test/**/*.spec.{js,cjs,mjs}',
]
```

but `*.spec.{js,cjs,mjs}` already includes everything, so if the environment is `node` it would also end up running test for `browser` it should ignore `browser`

**To Reproduce**
in the `tests` folder, create test:
- `node.spec.js`
- `browser.spec.js`
- `test.spec.js`

Run tests: `aegir test --target node`.

**Expected behavior**

Only the following tests should Run:
- `node.spec.js`
- `test.spec.js`

Instead all three run.