[DO NOT MERGE] Remove backwards-compatibility hack for $name idents

[Aaron1011]

Fixes #74616

There are still a large number of outstanding regressions, so this PR
can't be merged yet. I'm opening it to generate a newer 'try' build
for crate authors to test with.

Eventually, we'll want to do a crater run for this PR.

[rust-highfive]

r? @oli-obk

(rust_highfive has picked a reviewer for you, use r? to override)

[Aaron1011]

@bors try

[bors]

⌛ Trying commit 5641a9d with merge 2a3103302234c31d1bde8dc46902a24c869511e1...

[bors]

☀️ Try build successful - checks-actions, checks-azure
Build commit: 2a3103302234c31d1bde8dc46902a24c869511e1 (2a3103302234c31d1bde8dc46902a24c869511e1)

[Aaron1011]

@bors try

[bors]

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

1. git checkout feature/remove-nt-ident-hack (switch to your branch)
2. git fetch upstream master (retrieve the latest master)
3. git rebase upstream/master -p (rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self feature/remove-nt-ident-hack --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging src/test/ui/proc-macro/group-compat-hack/group-compat-hack.stdout
CONFLICT (content): Merge conflict in src/test/ui/proc-macro/group-compat-hack/group-compat-hack.stdout
CONFLICT (modify/delete): src/librustc_span/symbol.rs deleted in HEAD and modified in heads/homu-tmp. Version heads/homu-tmp of src/librustc_span/symbol.rs left in tree.
CONFLICT (modify/delete): src/librustc_expand/proc_macro_server.rs deleted in HEAD and modified in heads/homu-tmp. Version heads/homu-tmp of src/librustc_expand/proc_macro_server.rs left in tree.
CONFLICT (modify/delete): src/librustc_ast/token.rs deleted in HEAD and modified in heads/homu-tmp. Version heads/homu-tmp of src/librustc_ast/token.rs left in tree.
warning: inexact rename detection was skipped due to too many files.
warning: you may want to set your merge.renamelimit variable to at least 3574 and retry the command.
Automatic merge failed; fix conflicts and then commit the result.