Espresso sometimes does not wait enough for RecyclerView with setHasFixedSize(true) to load

Steps to reproduce:

1. Open attached project
2. Run ExampleInstrumentedTest couple of times, at least one test will fail eventually

If you add Thread.Sleep to the test or remove setHasFixedSize(true), tests will stop failing
[RecyclerTest.zip](https://github.com/android/android-test/files/2927839/RecyclerTest.zip)

Migrated from: https://issuetracker.google.com/123653014

Start with the attached RecyclerTest.zip project and run ExampleInstrumentedTest repeatedly, comparing behavior with setHasFixedSize(true), with it removed, and with the added Thread.Sleep. Use the intermittent failure as the baseline; done means the test reliably waits for the RecyclerView without requiring either workaround.

Written by the indexing model from the issue text.