Auto merge of #146443 - fmease:beta-less-greedy-maybe-const-bounds, r=fmease

[beta] Backport "Less greedily parse `[const]` bounds"

Backport of rust-lang/rust#146422.
Following https://forge.rust-lang.org/release/backporting.html#beta-backporting-in-rust-langrust.

Not part of some hypothetical future backport rollup because we're under time pressure as release procedures will commence very soon: https://forge.rust-lang.org/#current-release-versions, https://forge.rust-lang.org/release/process.html.

cc `@cuviper`