Revert "Share vdex files in the ART apex between architectures (..."

Revert submission 1254009-vdex-symlinks

Reason for revert: This causing some devices to fail to boot. See b/151836042 for details.
Reverted Changes:
Iced89071b:Expect vdex files in a target-independent director...
Ifbceb8457:Share vdex files in the ART apex between architect...

Change-Id: I5bd88f8e61d442eed921d840c90777a2750ddb16