Add t.Parallel() to java tests

Speeds up go test ./java from 32 seconds to 9 seconds.

Test: go test ./java
Change-Id: I4c6640e787c0744c6dfda03b7382839b452e24cf
diff --git a/java/robolectric_test.go b/java/robolectric_test.go
index 78326ab..ad0613e 100644
--- a/java/robolectric_test.go
+++ b/java/robolectric_test.go
@@ -71,6 +71,7 @@
 )
 
 func TestRobolectricJniTest(t *testing.T) {
+	t.Parallel()
 	if runtime.GOOS != "linux" {
 		t.Skip("requires linux")
 	}