infra_paths: keep cache paths super short to avoid long path issues
infra_paths: keep cache paths super short to avoid long path issues

BUG=623575

Review-Url: https://codereview.chromium.org/2102613002

CoherentLabs/depot_tools,primiano/depot_tools,primiano/depot_tools,CoherentLabs/depot_tools,primiano/depot_tools