Remove BOARD_VNDK_VERSION usage from Kati

As of VNDK deprecation, BOARD_VNDK_VERSION should not be referenced
anymore. This change removes BOARD_VNDK_VERSION references and related
logics from Kati, so VNDK deprecation can be fully set without flag.

Bug: 330100430
Test: AOSP CF build succeeded
Change-Id: I9ea5f1236268b99eb731ebf48afd9e595d06ab1a