Fix picker sync worker tests

The picker sync worker tests are updated to get an instance of the
Workers using the public TestWorkerBuilder lib instead of the private
Worker constructor.

Test: atest MediaProviderTests
Bug: 325099689
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:dcc33f3d3c9da9591755079ddc7a463cc62579aa)
Merged-In: I903bad9001f73c7a87f0bd46c199396213494c64
Change-Id: I903bad9001f73c7a87f0bd46c199396213494c64
5 files changed