Migrate ENABLE_RESPONSIVE_WORKSPACE to aconfig

- Keeping FeatureFlags.ENABLE_RESPONSIVE_WORKSPACE for local testing until aconfig is available in FlagFlipper
- Still reference ENABLE_RESPONSIVE_WORKSPACE in tests as aconfig still can't be mocked

Bug: 299935275
Test: manual
Change-Id: I092df894a3624dca6b9d381d56ada71d807547b5
3 files changed