Use vendor api level instead of sdk version

ro.vendor.api_level returns 202404 for 24Q2 release.
Use 202404 instead of __ANDROID_API_V__
This vendor api level may map to Android U in 24Q2.

Bug: 312798205
Test: atest vts_treble_vintf_vendor_test
Test: atest vts_treble_no_hidl
Change-Id: I02ad34fcd8e255d8acc171e1cc147ea619fb99b7
(cherry picked from commit 3fcf80c25023bfe61af1d61eb147d57ef65dde81)