Add StagedInstallInternalTest to adb TEST_MAPPING file

StagedInstallInternalTests contains test that verify staged installation
using adb commandline (e.g `adb install`) is working correctly.

Bug: 158314277
Test: atest --test-mapping system/core
Change-Id: Icc3bd464a91f31095316fbb85941e5e03089aaad