[fidldev] Use fx test -o not -v

This leads to lots of noise with the new fx test otherwise.

Change-Id: I1719f82df76266d53ca18bf03b9bf8f62f4114f8
Reviewed-on: https://fuchsia-review.googlesource.com/c/fidl-misc/+/1128119
Reviewed-by: Ian McKellar <ianloic@google.com>
diff --git a/fidldev/fidldev.py b/fidldev/fidldev.py
index 8973197..665bda4 100755
--- a/fidldev/fidldev.py
+++ b/fidldev/fidldev.py
@@ -145,8 +145,8 @@
     "--fx-test-args",
     "-t",
     help=
-    "Extra flags and arguments to pass to any invocations of fx test. The flag value is passed verbatim. By default, only '-v' is used.",
-    default='-v',
+    "Extra flags and arguments to pass to any invocations of fx test. The flag value is passed verbatim. By default, only '-o' is used.",
+    default='-o',
 )
 test_parser.add_argument(
     "--gtest_filter",