Add RootTargetPreparer for explicitly specifying the root dependency

Before, the test gets root implicitly via DeviceSetup which
wasn't intented.

Test: presubmit
Bug: 331655690
(cherry picked from https://android-review.googlesource.com/q/commit:5ed9e351487e45fd7c4a728e555aa8b4ce870829)
Merged-In: Ia81ba888aca96ca626c2a2464e3f0e9146bae231
Change-Id: Ia81ba888aca96ca626c2a2464e3f0e9146bae231