Suppress deprecation warnings in LegacyTypeTrackerTest.

This saves dozens of warnings every time FrameworkNetTests is
compiled. There is nothing we can do about those warnings because
LegacyTypeTracker's reason for existence is to power deprecated
APIs.

Test: m FrameworksNetTests
Change-Id: I4d65b0aade493e12b56a94247efbf9d1ad7bb4b9