[autotest] Fix Cr label of automated bug filing for network3g suites.

The Cr label was incorrectly spelled. It should be Cr-OS-Systems-Mobile
instead of Cr-OS-System-Mobile.

BUG=chromium:240793
TEST=Schedule suite runs with failed tests and check filed bugs for
sensible default labels.

Change-Id: Ibaf585e5208c8fd883e0a2449513ed42e8b97c2f
Reviewed-on: https://gerrit.chromium.org/gerrit/55553
Commit-Queue: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
diff --git a/test_suites/control.network3g b/test_suites/control.network3g
index 9ad06a0..a3be3ef 100644
--- a/test_suites/control.network3g
+++ b/test_suites/control.network3g
@@ -27,7 +27,7 @@
 # filing bugs on tests that are a part of this suite. If left unspecified
 # the bug filer will fallback to it's defaults.
 _BUG_TEMPLATE = {
-    'labels': ['Cr-OS-System-Mobile'],
+    'labels': ['Cr-OS-Systems-Mobile'],
     'owner': '',
     'status': None,
     'summary': None,