Wifi CTS: Add coverage for WifiNl80211Manager#testSetOnServiceDeadCallback

This method should always be called during Wifi
boot up. However, the coverage tool may not detect
this API usage depending on when it starts
tracking API calls.

Bug: 158764177
Test: atest WifiNl80211ManagerTest
Change-Id: Iacd6f317107a6ac80976fb02b399b890d32c1cc9