Change eslint output to human readable

Today in the build logs, eslint prints a json payload of every file it
checked, regardless of whether there are errors present, which isn't
really human readable and clogs up log space.

This commit changes to the "stylish" output which is human readable.
Examples of which are in the eslint docs[1].

Tested: ran a build, and observed the json gone, and a much more
readable log present.

```
eslint . --ignore-path .gitignore --no-eslintrc -c /build/eslint-global-config.json                --ext .json --format=stylish                --resolve-plugins-relative-to /usr/local/lib/node_modules                --no-error-on-unmatched-pattern
```

[1]: https://eslint.org/docs/latest/user-guide/formatters/#stylish

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ib13630bdce65351215324add4c9c3233fff06c61
1 file changed