autotest: quieten mav draining

Tools/autotest/common.py

@@ -1644,7 +1644,7 @@ class AutoTest(ABC):
                 continue
             util.pexpect_drain(p)
 
-    def drain_mav_unparsed(self, mav=None, quiet=False, freshen_sim_time=False):
+    def drain_mav_unparsed(self, mav=None, quiet=True, freshen_sim_time=False):
         if mav is None:
             mav = self.mav
         count = 0
@@ -1665,7 +1665,7 @@ class AutoTest(ABC):
         if freshen_sim_time:
             self.get_sim_time()
 
-    def drain_mav(self, mav=None, unparsed=False, quiet=False):
+    def drain_mav(self, mav=None, unparsed=False, quiet=True):
         if unparsed:
             return self.drain_mav_unparsed(quiet=quiet, mav=mav)
         if mav is None: