Kill ConfirmDeviceCredentialBaseActivity when it is no longer visible

The problem is because ConfirmDeviceCredentialActivity is not created
again when the new intent is fired. Add no history flag to kill it once
it is not visible. We have the exclude from recent flag anyway, so
finishing it should be fine.

Bug: 27564634
Change-Id: I2e22f3d7a108f8fbad5f27894b1a92f19d25bcda