Use new UserChecker to configure users for cts with cmdline flags

Test: run cts --user-type secondary -m CtsMultiUserTestCases -m
CtsMultiUserHostTestCases -m CtsDevicePolicyManagerTestCases

Bug: 126246061
Change-Id: I4d9b6421d60dc2151b27dc74804601e3dcf7fe6a
diff --git a/tools/cts-tradefed/res/config/cts-system-checkers.xml b/tools/cts-tradefed/res/config/cts-system-checkers.xml
index b3adb69..62744bf 100644
--- a/tools/cts-tradefed/res/config/cts-system-checkers.xml
+++ b/tools/cts-tradefed/res/config/cts-system-checkers.xml
@@ -14,6 +14,7 @@
      limitations under the License.
 -->
 <configuration description="CTS system checker configs">
+    <system_checker class="com.android.tradefed.suite.checker.UserChecker" />
     <system_checker class="com.android.compatibility.common.tradefed.targetprep.NetworkConnectivityChecker" />
     <system_checker class="com.android.tradefed.suite.checker.KeyguardStatusChecker" />
     <system_checker class="com.android.tradefed.suite.checker.SystemServerStatusChecker" />