Replace updateAllPermissions() with onStorageVolumeMounted().

The two calls in PackageManagerService.systemReady() is moved into
PermissionManagerService.onSystemReady(). The other two calls are
really about storage volumes so rename them to
onStorageVolumeMounted() to be a proper API.

Bug: 158736025
Test: presubmit
Change-Id: Ic182f0661b687168ea3b008365a4ce42fc0b7150