[automerger skipped] Introduce build variable `OVERRIDE_TARGET_FLATTEN_APEX`. am: 1dbb0c3d1e -s ours

am skip reason: Change-Id Ib9ccae38430340de38e4758b4f55df2c65ea60d5 with SHA-1 b3a503df7f is in history

Change-Id: I857709a0805622d6c16a44b393ab1f38cacaddee