Add a suspension check to SuspendedAppActivity

ACTION_PACKAGES_SUSPENSION_CHANGED can be delivered without suspension
changes, which ends up finishing SuspendedAppActivity and CTS fails.

This CL adds a check to make sure suspended state changed before
finishing it.

Bug: 245426112
Test: cts-tradefed run cts -m CtsDevicePolicyManagerTestCases -t
      com.android.cts.devicepolicy.MixedManagedProfileOwnerTest#testSuspendPackageWithPackageManager
Change-Id: I74116b1c8508239b4026883916a89bfdac902bae