TestDPC SetAutoTimeRequired disabled in managed profile

* Set auto time required preference should be disabled
  if the TestDpc instance is in managed profile.

Bug: 156620695
Test: Manual, verify TestDPC preference is disabled on a
      managed profile.
Change-Id: I6ff599f84bdff3b269ef18afd65beed5577760ca

Author: Alex Johnston

app/src/main/res/xml/device_policy_header.xml

@@ -672,6 +672,7 @@
         <com.afwsamples.testdpc.common.preference.DpcSwitchPreference
             android:key="set_auto_time_required"
             android:title="@string/set_auto_time_required"
+            testdpc:user="notManagedProfile"
             testdpc:minSdkVersion="L" />
         <com.afwsamples.testdpc.common.preference.DpcSwitchPreference
             android:key="set_auto_time"