Revert^2 "READ_DROPBOX_DATA permission"

Starting from Android V, READ_DROPBOX_DATA permission will guard the data in Dropbox instead of READ_LOGS permission.
In DropBoxManagerService.java, TargetSdkVersion gating is used to differentiate between permission checking requirements for Android V and after and Android U and before. Android U and before can continue using the READ_LOGS permission, while Android V and after require the READ_DROPBOX_DATA permission.

This is a revert of a revert(ag/25040247)

Test: atest DropBoxTests
Bug: 296060945
Change-Id: I1978a3a959b575e2617bd46c1c5753a847c21604