Move init.vndk-*.rc to system_ext/etc/gsi

Orgianlly, init.vndk-*.rc are placed under system_ext/etc/init.
`init` always run all thse .rc files. The patch move these .rc
files to system_ext/etc/gsi to avoid the problem.

Bug: 185457479
Test: build gsi_arm64-userdebug; check the files under system_ext/
Change-Id: Iee67d6e2e872cf3cb1dd1014925ed0249c1e7e2d