matrix: IGNORE_TARGET_FCM_VERSION -> VINTF_*

All "private" environment variables to assemble_vintf
(inserted by the build rules, not build system variables)
should have this prefix (to distinguish against,
e.g. PRODUCT_ENFORCE_VINTF_MANIFEST)

Test: m framework_compatibility_matrix -j

Bug: 65028233
Change-Id: Iaefa88cefc0918fb86235ea6fcd8e367cbd82788
Merged-In: Iaefa88cefc0918fb86235ea6fcd8e367cbd82788
1 file changed