[clang-tools-extra] [clang-doc] Move Info types into arenas (PR #190054)

[via cfe-commits]

dyung wrote:

> > The pr is in #191644

> I'll give your change a try and see what happens. 

I manually applied your change to the bot, but unfortunately the failures are still present. Since tomorrow is Sunday and not likely to be a high commit traffic date, I'm fine with leaving the bot failing for the time being if you want further time to investigate.

https://github.com/llvm/llvm-project/pull/190054