Rollup merge of #91087 - rukai:fix_test_nll_revisions, r=jackh726

Rollup merge of #91087 - rukai:fix_test_nll_revisions, r=jackh726

Remove all migrate.nll.stderr files

There are a few ui tests that setup the revisions like:
```rust
// revisions: migrate nll`
// [nll]compile-flags: -Zborrowck=mir
```

However most of them fail to disable the nll compare mode like this:
```rust
// ignore-compare-mode-nll
```

This ends up generating confusing files ending in `.migrate.nll.stderr` because the nll compare mode is run on top of the migrate revision.

This PR fixes this by adding `ignore-compare-mode-nll` to these tests.

I would have just made these tests use compare modes instead but I assume the reason these tests are messing around with revisions instead of just letting the nll compare mode do its thing is to enforce error annotations for both migrate and nll.
Relying on just compare modes would only have the error annotations for migrate.