Remove RELEASE_APEX_USE_EROFS_PREINSTALLED

Because it was add manually, Gantry can advance it to the next stage. To
fix the issue, let's revert it manually, then advance it using Gantry.

Bug: 457270815
Flag: RELEASE_APEX_USE_EROFS_PREINSTALLED
Test: m && deapexer info --print-payload-type <apex>
     # prints ext4
Change-Id: I06ada9d0d5db86cc71e3ee4f395e0522af3adec0