Trying to flutter run the espresso example fails due to needing to enable multidex. This wasn't caught in CI because flutter build succeeds, and the example is never run because it doesn't have integration tests, and is on the exclusion list.

Ideally we should:

• Enable multidex
• Add a no-op integration test (there's some precedent for this, such as image_picker_android, which can't be tested via integration test due to modal native UI)
• Remove the exclusion from script/configs/exclude_integration_android.yaml (and in fact we could then remove that file, and the reference to it from CI configuration)

That would cause the example to be run in CI, so that this couldn't happen again.

/cc @reidbaker