[CI] Switch Emscripten CI job to mac runners
Summary:
This reverts D10341 because of issues described in ENG-6879
Reverts D10341
Test Plan:
- -> should pass
- Makes some changes in DB C++ code without committing .wasm changes -> should fail
- Run Emscripten locally and commit files -> should pass
See below
Reviewers: michal, atul
Reviewed By: atul
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D11156