Fix extra test runner args command line.

- Use one -P flag per extra argument. This way we don't need to
  interpret (split) the values.
- Change the property name to use "android" prefix (like properties
  from AndroidProject) and the same name as the DSL option.
- Stop using the env variable.

Change-Id: Ie48d1805194ee9591c35b5fa73a3175bbcf337bb
2 files changed