[test][prefix] Add assets with too long descriptions

This will allow to improve tests also in beat/beat.cmdline>
4 jobs for test_prefix_add_new_invalid_assets in 22 minutes and 9 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #192004
docker-build
build_linux_36

00:13:39

64.0%
passed #192005
docker-build
build_linux_37

00:13:36

64.0%
passed #192002
macosx
build_macosx_36

00:22:09

64.0%
passed #192003
macosx
build_macosx_37

00:22:02

64.0%