[llvm] github: Add tablegen directories to PR autolabeler (PR #109129)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> I thought the plan was to get rid of the pr-subscribers lists. I removed myself from all of those a while ago

Maybe eventually if Github lets you do label-based subscriptions for PRs, but I believe they only support that for issues currently. That's still how notifications are done currently as far as I can tell.

https://github.com/llvm/llvm-project/pull/109129