Relax missing service check for normal apps.

The new missing-service behavior was mostly added for core system
components, so don't wtf() when normal apps ask for missing services.

Continue to emit one-line log for third-party apps so they know why
getSystemService() might be returning null.

Test: builds, boots
Bug: 33109365
Change-Id: I3a6118a3db570d796a26da5b8d63015b13e53a87