Add WTF when a system server wrapper can't be found

Context.getSystemService() shouldn't return null, but sometimes we observer it.
Add WTFs to investigate it.

Bug: 149406139
Test: Boot with "adb logcat | grep -i wtf" and make sure no wtf is logged
Change-Id: I64c6776cedaeb534d98621db2955d585e6846b8d
1 file changed