Rephrase dialog message of clear storage dialog for security concern am: 7fd0ece6f4 am: 204f82d6c4 am: ac38fc7f32 am: 70b7658b74 am: e49a0f6bdd am: 5a142ad048

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/16101569

Change-Id: Idfe57ae775f4542ea158cb14e0f012de5bb9d795