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

Rephrase dialog message of clear storage dialog for security concern am: 7d22136f am: 337e182e am: d67d983b am: 41e6a117 am: 43d833ae am: f0cc223e am: 0d3acd78

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/16101568

Change-Id: Iea13f55278bc03defa39c87a4d1f8f9deb4581f6