Use RELEASE_CREATE_ACONFIG_STORAGE_FILE to create aconfig files

This matches the kati packaging system implementation

Test: verified that these files do not appear in `fileList` of
generic_system_image when building with a TARGET_RELEASE that is not
`trunk_staging` or `trunk`
Bug: 369678122

Change-Id: Ieb585a8e1d20bc939fddfad9bafcecaaf767fa4e