remove the extra slash from insert uri

withAppendedPath API adds extra slash before appending,
there is no need to add it twice.

Bug: 64161300
Test: runtest --path
tests/src/com/android/providers/telephony/SmsProviderTest.java --test-method testInsertUri

Change-Id: Ie7e1e1532c1e666752a5513abd345fb3d5816145
4 files changed