This reverts commit 93573de216.
Fails in the devicelab:
```
run:stderr: A problem occurred evaluating project ':app'.
run:stderr: > Could not resolve all files for configuration 'classpath'.2018-10-23T10:46:46.335864:
run:stderr: > Could not find aapt2-proto.jar (com.android.tools.build:aapt2-proto:0.3.1).2018-10-23T10:46:46.335960:
run:stderr: Searched in the following locations:2018-10-23T10:46:46.336048:
```
Adds an integration devicelab test that runs an Android app with two
custom named isolates. Tests that the isolate names are present and that
it's possible to attach to just one of the isolates.
Fixesflutter/flutter#22009
