Use the MTE flag only for guarding policy identifier

Enable the implementation of storing the MTE policy in the
DevicePolicyEngine by default.

Filter the MTE policy identifier in the PolicyUpdateReceiver if the flag
is not set as it means the constant associated with the policy is not
part of the public API.

Bug: 378931989
Test: atest CtsSecurityTestCases:android.security.cts.advancedprotection.MemoryTaggingExtensionTest
Test: CtsDevicePolicyTestCases:android.devicepolicy.cts.PolicyUpdateReceiverTest
Test: CtsDevicePolicyTestCases:android.devicepolicy.cts.DeviceManagementCoexistenceTest
Flag: android.app.admin.flags.set_mte_policy_coexistence
Change-Id: I88855596fe6185cd711bbb9397f3c8220308a705