Auto merge of #34652 - jseyfried:fix_expansion_perf, r=nrc

Auto merge of #34652 - jseyfried:fix_expansion_perf, r=nrc

Fix expansion performance regression

**syntax-[breaking-change] cc #31645**

This fixes #34630 by reverting commit 5bf7970 of PR #33943, which landed in #34424.

By removing the `Rc<_>` wrapping around `Delimited` and `SequenceRepetition` in `TokenTree`, 5bf7970 made cloning `TokenTree`s more expensive. While this had no measurable performance impact on the compiler's crates, it caused an order of magnitude performance regression on some macro-heavy code in the wild. I believe this is due to clones of `TokenTree`s in `macro_parser.rs` and/or `macro_rules.rs`.

r? @nrc