[autotest] Remove os_type in board name used by suite scheduler

This change forces suite scheduler to look for android/brillo duts using board
label without os type. That is, using board:shamu instead of
board:android-shamu.

BUG=chromium:627264
TEST=local run
/usr/local/autotest/site_utils/suite_scheduler/suite_scheduler.py \
  -d /usr/local/autotest/logs -f dshi/test_android_suite_scheduler.ini  \
  -e nightly  -i  git_mnc-release/shamu-userdebug/2457013   \
  -o android

DEPLOY=suite scheduler

Change-Id: Ie83735825275c02424348a8dcf550d16382a3ccc
Reviewed-on: https://chromium-review.googlesource.com/362400
Commit-Ready: Dan Shi <dshi@google.com>
Tested-by: Dan Shi <dshi@google.com>
Reviewed-by: Kevin Cheng <kevcheng@chromium.org>
diff --git a/site_utils/suite_scheduler/task.py b/site_utils/suite_scheduler/task.py
index 4fbc1ca..c14c400 100644
--- a/site_utils/suite_scheduler/task.py
+++ b/site_utils/suite_scheduler/task.py
@@ -277,7 +277,7 @@
             for target in lc_targets.split(','):
                 board_name, _ = server_utils.parse_launch_control_target(
                         target.strip())
-                boards += '%s-%s,' % (os_type, board_name)
+                boards += '%s,' % board_name
             boards = boards.strip(',')
 
         return keyword, Task(section, suite, specs, pool, num, boards,