Fix deadlock in NetworkLoggingHandler

Stop NetworkLoggingHandler holding a lock
when calling back into DevicePolicyManagerService.

Test: cts-tradefed run cts -m CtsDevicePolicyManagerTestCases --test com.android.cts.devicepolicy.DeviceOwnerTest#testNetworkLoggingWithSingleUser
Test: cts-tradefed run cts -m CtsDevicePolicyManagerTestCases --test com.android.cts.devicepolicy.DeviceOwnerTest#testNetworkLoggingWithTwoUsers

Bug: 62966480
Change-Id: I41c3edca8922008a9d838d71ddcc50883699bc74