refactor(datastore): Refactor test names and make subscription events more sample app like

[stocaaro]

Description of changes

Outcome:

• Test names changed to align with the harness features used per test
• Wait for all subscriptions to be published before proceeding (remove a race condition between test assertions and subscription updates)

Description of how you validated changes

Tests updated in reference to how users receive settled updates twice in sample apps (once via mutation response and then later via subscription update).

Related changes

1. refactor(datastore): Move conflict resolution tests to their own file #12728
2. refactor(datastore): Refactor conflict resolution tests optimize for concise/readable #12732
3. 🌱 refactor(datastore): Refactor test names and make subscriptions more latent / realistic
4. test(datastore): Add OptimisticConcurrency tests #12795
5. fix(datastore): Update outbox comparison logic to fix update versioning problems stocaaro/amplify-js#87

Checklist

• PR description included
• yarn test passes
• Tests are changed or added

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[david-mcafee]

Since these changes result in different test assertions, I think I'd like to see a few comments explaining exactly what's happening (and why) - specific comments requesting those changes are included inline.

[david-mcafee]

Thanks for responding to my previous questions on this one! Left two minor (non-blocking) suggestions.