[llvm] [llvm-strip] Remove empty SHT_GROUP sections. (PR #97141)

[Dmitriy Chestnykh via llvm-commits]

chestnykh wrote:

> > Currently llvm-strip in --strip-debug mode doesn't remove such sections.
> 
> Thanks for noticing this. This applies to other section removal operations like --remove-section, so another test will be useful

Added some new runs of llvm-strip + llvm-readelf

https://github.com/llvm/llvm-project/pull/97141