Fix eslint-as-if-foss CI job
What does this MR do?
The eslint-as-if-foss CI job currently runs the eslint NPM script, which has been deprecated in favor lint:eslint:all.
Since its deprecation, eslint still looks like it works as it always passes and runs in under a second, which is misleading.
This updates the CI job to use the proper NPM script that runs ESLint on the whole codebase.