[CI] Get rid of touch JSON commands in CI

Summary:
Linear Issue: https://linear.app/comm/issue/ENG-1190/get-rid-of-touch-json-commands-in-ci

We were previously creating empty JSON files via the touch command to appease flow in the ESLint/Flow/Test workflows on GitHub and Buildkite.

However, we no longer need to do this as of https://phabricator.ashoat.com/D4097.

Test Plan: See if Buildkite CI passes (on arc diff) and if GH Actions CI passes (on arc land)

Reviewers: ashoat, palys-swm, def-au1t, benschac

Reviewed By: ashoat

Subscribers: Adrian, yayabosh

Differential Revision: https://phabricator.ashoat.com/D4114