getDeviceOwnerDeletedPackageMsg() should call clearCallingIdentity()

DevicePolicyResourcesManager should be called in the context of
system_server instead of the calling app to avoid UID and package
name mismatch.

Bug: 246487618
Test: atest SessionCommitBroadcastTest
Change-Id: I1d27c7cd879d440abcf834830563368e50f521f2