nightly#122 adaptations for nightly-2025-11-21

Stream: nightly-testing

[github mathlib4 bot]

chore: adaptations for nightly-2025-11-21 nightly#122 Please review this PR. At the next toolchain release this diff will land in 'master'.

[Kevin Buzzard]

I sometimes merge these PRs but 95% of the changes made in the last couple of days are completely beyond my pay grade so I'm not going to merge these. It would be good if someone could look at them or else nightly testing will just get more and more behind.

[Kim Morrison]

After merging master -> bump/v4.27.0 -> bump/nightly-2025-11-21 again, the diff became quite small, so I merged.