Release testing version of app with updated keystore

[ktohalloran]

Based on research as a part of #204, this app is already enrolled and being signed via Google App Signing. Therefore, we need to change to releasing via a new upload key and via App Bundle instead of APK. In order to isolate as many unknowns as possible, we should release an App Bundle with the old key, then use that process to release with the new key once it has been reset. This task is to complete the second half of this double release.

At the minimum, this task should include:

• Sign the app with the new upload key by following the instructions here.
• Follow the procedure for releasing via App Bundle from issue #205

If we have time, we should: This should be spun out as its own issue if we don't end up having time in this card.

• Test the testing release version of the app via the Android emulator and by finding an Android user able to try the test version on their phone

End goal:

• If we are able to successfully release and test within the scope of this issue, then the end goal of this task is to release the test version. If not, the end goal is to write up any follow up issues.

[ktohalloran]

With the addition of #209, our end goal here is no longer to release a new version of the app but just to test the new upload key by releasing a test version. The new upload key does work and in the process, I noticed some strangeness with the use of release.properties, which has been addressed in PR #212.