Update Android packages cache key

Summary:
Packages are now defined in `scripts/.tests.env`, so the checksum is updated accordingly.

We also throw away the cache if the checksum fails as not doing so may prevent us from picking up new packages due to the filesystem check in `scripts/android-setup.sh`#getAndroidPackages(), as the presence of the `installed-dependencies` file restored from cache will incorrectly flag all deps as being installed.
Closes https://github.com/facebook/react-native/pull/19298

Differential Revision: D8025918

Pulled By: hramos

fbshipit-source-id: 189492baac2fea39280884ea20e376a368e23c2e