sync: Remove smart sync override manifest when not in smart sync mode

When syncing with the -s or -t option, a smart_sync_override.xml file
is created. This file is left in the file system when syncing again
without the -s or -t option.

Remove the smart sync override manifest, if it exists, when not using
the -s or -t option.

Change-Id: I697a0f6405205ba5f84a4d470becf7cd23c07b4b