Enable testOnSmartspaceMediaDataLoaded

Enables
testOnSmartspaceMediaDataLoaded_hasNoneMediaTarget_callsRemoveListener
in MediaDataManagerTest. The test was using foreground executor while a
new thread was being used and can't be tracked.
Used uiExecutor like other smartspace media session and change the test
to use uiExecutor. And also added smartspace manager as a constructor
instead of using Context.getSystemService().

Bug: b/233283726
Test: atest MediaDataManagerTest.
Test: used go/abtd to test on a certain device that made this bug appears.
Change-Id: Ia7d14092542c3ff33b8684d8f8fe31096443354d