Revert "Disable UserCloudPolicyManagerChildTest.PolicyForChildUser on some bots"

This reverts commit 746928a6.

Reason for revert: The test is stable again after fixing https://crbug.com/976987.

Original change's description:
> Disable UserCloudPolicyManagerChildTest.PolicyForChildUser on some bots
> 
> The bots are deterministically failing on bots that have libassistent.
> 
> TBR=antrim@chromium.org
> 
> Bug: 1005454
> Test: none
> Change-Id: Ic783f307a346bb3a1f2cb8865aef4a9d93234e1f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829344
> Reviewed-by: Pavol Marko <pmarko@chromium.org>
> Commit-Queue: Pavol Marko <pmarko@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#700920}

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1005454
Change-Id: I5dfafde6883c7f93bdc7a10f1793db7103f3740c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1852431Reviewed-by: Sergey Poromov <poromov@chromium.org>
Reviewed-by: Oleg Davydov <burunduk@chromium.org>
Commit-Queue: Oleg Davydov <burunduk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704663}

chrome/browser/chromeos/policy/user_cloud_policy_manager_chromeos_browsertest.cc

@@ -10,7 +10,6 @@
 #include "base/stl_util.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/values.h"
-#include "build/buildflag.h"
 #include "chrome/browser/chromeos/login/users/chrome_user_manager.h"
 #include "chrome/browser/prefs/session_startup_pref.h"
 #include "chrome/browser/profiles/profile.h"
@@ -21,7 +20,6 @@
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/test/base/mixin_based_in_process_browser_test.h"
-#include "chromeos/assistant/buildflags.h"
 #include "chromeos/constants/chromeos_switches.h"
 #include "components/arc/arc_features.h"
 #include "components/arc/arc_prefs.h"
@@ -228,15 +226,7 @@ IN_PROC_BROWSER_TEST_P(UserCloudPolicyManagerTest,
 
 using UserCloudPolicyManagerChildTest = UserCloudPolicyManagerTest;
 
-// TODO(https://crbug.com/1005454): This test is failing on bots that show the
-// assistent opt-in screen.
-#if BUILDFLAG(ENABLE_CROS_LIBASSISTANT)
-#define MAYBE_PolicyForChildUser DISABLED_PolicyForChildUser
-#else
-#define MAYBE_PolicyForChildUser PolicyForChildUser
-#endif
-IN_PROC_BROWSER_TEST_P(UserCloudPolicyManagerChildTest,
-                       MAYBE_PolicyForChildUser) {
+IN_PROC_BROWSER_TEST_P(UserCloudPolicyManagerChildTest, PolicyForChildUser) {
   policy::BrowserPolicyConnector::SetNonEnterpriseDomainForTesting(
       "example.com");
   EXPECT_TRUE(policy::BrowserPolicyConnector::IsNonEnterpriseUser(