Update uiautomator references in external/mobile-data-download

* Remove unused dependencies.
* Replace "ub-uiautomator" (v2.2.0) with
  "androidx.test.uiautomator_uiautomator" (v2.3.0).

Bug: 235842600
Test: presubmit
Change-Id: Idd8baaf31aaba6a466fedba64ca3e50b30932e5e
3 files changed