Make getSystemProperty return ListenableFuture

Bug: 157851487
Test: Not applicable
Change-Id: I639a00bce63f0fa5bbe64b842d2a3333093bc5f1
1 file changed
tree: 8923fa97cda16f8868149b65fddb8eb4122548f1
  1. firebase-testing/
  2. test-recorder/