configs: Remove old boot files

configs: Remove old boot files

Most of these "rcS" scripts are only useful for specific disk images
that have long been lost to the gem5 community. This commit deletes all
of these scripts. It keeps the generally useful hack_back_cktp script
and the bbench scripts that work with the android images that are still
available.

In the future, these remaning scripts should be moved to the gem5
resources repository.

Issue-on: https://gem5.atlassian.net/browse/GEM5-350
Change-Id: Iba99e70fde7f656e968b4ecd95663275bd38fd6e
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28507
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>