tradefed_test: reduce timout for breaking lock.

Only wait about 10 minutes instead of an hour before breaking the lock
and failing the test. This should reduce impact of this failure on the
CQ (one job will die faster, but most jobs will continue faster).

We still need to root cause the problem.

BUG=b:70539494
TEST=None.

Change-Id: Icc14ea26720650e56faa90e7d6969ada8583626b
Reviewed-on: https://chromium-review.googlesource.com/822030
Reviewed-by: Kazuhiro Inaba <kinaba@chromium.org>
Tested-by: Ilja H. Friedel <ihf@chromium.org>
(cherry picked from commit af15bfd4b7c345ef00c3af968db79c134c2a9996)
Reviewed-on: https://chromium-review.googlesource.com/822302
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
diff --git a/server/cros/tradefed_test.py b/server/cros/tradefed_test.py
index d128971..5b9e5ea 100644
--- a/server/cros/tradefed_test.py
+++ b/server/cros/tradefed_test.py
@@ -218,9 +218,9 @@
             logging.info('Waiting for cache lock...')
             filelock.acquire(random.randint(1, 5))
         except (lockfile.AlreadyLocked, lockfile.LockTimeout):
-            if attempts > 1000:
-                # Normally we should aqcuire the lock in a few seconds. Once we
-                # wait on the order of hours either the dev server IO is
+            if attempts > 200:
+                # Normally we should aqcuire the lock immediately. Once we
+                # wait on the order of 10 minutes either the dev server IO is
                 # overloaded or a lock didn't get cleaned up. Take one for the
                 # team, break the lock and report a failure. This should fix
                 # the lock for following tests. If the failure affects more than