Assert getService does not return nullptr

Make sure getService return value is not null before running
testcase

Test: make vts -j40 && vts-tradefed run commandAndExit vts -m
VtsHalConfigstoreV1_0Target
Bug:62931371

Merged-In: I432e07c0c61a308b814d88cab9027a95ff24d8b5
(cherry picked from commit 60ff24c6)

Change-Id: Id9bb2a3fb2c4caf02c7e03c1529cefe2570c5453