Rephrase dialog message of clear storage dialog for security concern am:...

Rephrase dialog message of clear storage dialog for security concern am: 6024ea55 am: 2d08d347 am: ebcc8d97 am: ff0a9260 am: c4ac4388 am: 6a3f7fac

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/16101567

Change-Id: I15fe0afabbcce1d99f81e4893e2098f0fec62821