Remove libs message about ACPs from triagebot

The libs team is currently reworking the ACP process and we don't want
to encourage people to submit new ACPs in the meantime.

triagebot.toml

@@ -371,31 +371,6 @@ cc = ["@GuillaumeGomez"]
 message = "Some changes might have occurred in exhaustiveness checking"
 cc = ["@Nadrieril"]
 
-[mentions."library"]
-message = """
-Hey! It looks like you've submitted a new PR for the library teams!
-
-If this PR contains changes to any `rust-lang/rust` public library APIs then \
-please comment with `@rustbot label +T-libs-api -T-libs` to tag it \
-appropriately. If this PR contains changes to any unstable APIs please edit \
-the PR description to add a link to the relevant [API Change \
-Proposal](https://std-dev-guide.rust-lang.org/feature-lifecycle/api-change-proposals.html) \
-or [create one](https://github.com/rust-lang/libs-team/issues/new?assignees=&labels=api-change-proposal%2C+T-libs-api&template=api-change-proposal.md&title=%28My+API+Change+Proposal%29) \
-if you haven't already. If you're unsure where your change falls no worries, \
-just leave it as is and the reviewer will take a look and make a decision to \
-forward on if necessary.
-
-Examples of `T-libs-api` changes:
-
-* Stabilizing library features
-* Introducing insta-stable changes such as new implementations of existing \
-  stable traits on existing stable types
-* Introducing new or changing existing unstable library APIs (excluding \
-  permanently unstable features / features without a tracking issue)
-* Changing public documentation in ways that create new stability guarantees
-* Changing observable runtime behavior of library APIs
-"""
-
 [mentions."src/librustdoc/clean/types.rs"]
 cc = ["@camelid"]