Make TileQueryHelperTest less flaky

Remove creation of a real HotspotTile and instead use a mock and verify
things in order.

This fixed test shows that a not available tile has its spec set before
it's destroyed.

Fixes: 155744376
Test: atest TileQueryHelperTest
Change-Id: Icdc98e2e4550427815900ac6fee12c7a15bd5dc7