[llvm] [TableGen][GlobalISel] Emit Comment with MatchTable Size (PR #74701)

[Pierre van Houtryve via llvm-commits]

Pierre-vh wrote:

> Could this be printed as not-comment as the array size?

It can be a separate change if we want that too, I want to keep the metric consistent here (bytes instead of array size) so we can see the changes better in #74429 

https://github.com/llvm/llvm-project/pull/74701