Fix grpc/datastore tests

[jonasfj]

No description provided.

[jonasfj]

There is still a timeout, but at least this fixed most of the test cases :)

[appengine]$pub run test
00:35 +27: test/integration/grpc_datastore_test.dart: e2e_datastore empty_commit negative_empty_commit_xg
  Skip: Existing failure
01:12 +29 ~1 -1: test/integration/grpc_datastore_test.dart: e2e_datastore query query [E]
  TimeoutException after 0:00:30.000000: Test timed out after 30 seconds.
  package:test_api  Invoker._onRun.<fn>.<fn>.<fn>

01:40 +39 ~1 -1: Some tests failed.
[appengine]$

[jonasfj]

Fixed the last test by bumping the timeout...

[appengine]$pub run test
00:37 +27: test/integration/grpc_datastore_test.dart: e2e_datastore empty_commit negative_empty_commit_xg
  Skip: Existing failure
01:44 +40 ~1: All tests passed!
[appengine]$

[domesticmouse]

QQ, do you think this will fix dart-lang/labs#167?

[jonasfj]

Doubtful, this only touches the test files :)