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/proto_test.go b/java/proto_test.go
index d1cb714..5b184b6 100644
--- a/java/proto_test.go
+++ b/java/proto_test.go
@@ -28,6 +28,7 @@
 `
 
 func TestProtoStream(t *testing.T) {
+	t.Parallel()
 	bp := `
 		java_library {
 			name: "java-stream-protos",