Revert "[tools] Add retries when trying to discover the device"

This reverts commit f1741bdd.

Reason for revert: forgot to import 'time' module

Original change's description:
> [tools] Add retries when trying to discover the device
> 
> This is an experimental change that may help mitigate the issue.
> 
> TBR=machenbach@chromium.org
> 
> No-Try: true
> No-Tree-Checks: true
> Bug: chromium:893593
> Change-Id: Ideb74a83b9937dbe917e8c7c93305d9824b48a93
> Reviewed-on: https://chromium-review.googlesource.com/c/1339419
> Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
> Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#57556}

TBR=machenbach@chromium.org,sergiyb@chromium.org

Change-Id: I5ae591e099f630fdb4cd63d18bfb2f1bf347f929
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:893593
Reviewed-on: https://chromium-review.googlesource.com/c/1339519Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57557}

tools/testrunner/local/android.py

@@ -50,13 +50,8 @@ class _Driver(object):
     devil_chromium.Initialize()
 
     if not device:
-      # Detect attached device if not specified. Retry 3 times with 60 second
-      # sleep in-between.
-      for _ in range(3):
-        devices = adb_wrapper.AdbWrapper.Devices()
-        if devices:
-          break
-        time.sleep(60)
+      # Detect attached device if not specified.
+      devices = adb_wrapper.AdbWrapper.Devices()
       assert devices, 'No devices detected'
       assert len(devices) == 1, 'Multiple devices detected.'
       device = str(devices[0])