Fix OS::GetFileSizeBytes().

Also improve CHECKs in dex2oat_image_test and

    Revert "Disable failing test."
    This reverts commit f0e3d9fc0354dfebb06d6930515c315ecc76fe1d.

Test: m test-art-host-gtest-dex2oat_image_test
Bug: 74375666
Change-Id: Iebeceb5a1cdc9d80a76039f52e826711085a7626
2 files changed