Rehome 21 tests/ui/issues/ tests to other subdirectories under tests/ui/

[Oneirical]

#143902 divided into smaller, easier to review chunks.

Part of #133895

Methodology:

1. Refer to the previously written tests/ui/SUMMARY.md
2. Find an appropriate category for the test, using the original issue thread and the test contents.
3. Add the issue URL at the bottom (not at the top, as that would mess up stderr line numbers)
4. Rename the tests to make their purpose clearer

Inspired by the methodology that @Kivooeo was using.

r? @jieyouxu

[rustbot]

jieyouxu is currently at their maximum review capacity.
They may take a while to respond.

[rustbot]

This PR modifies tests/ui/issues/. If this PR is adding new tests to tests/ui/issues/,
please refrain from doing so, and instead add it to more descriptive subdirectories.

[jieyouxu]

For future PRs like this where you have both moves and edits, can you make sure to split the changes into two commits, with commit 1 being move-only, and commit 2 being edits? This is intended to make it easier to navigate git history. I wouldn't worry so much about PRs you already have opened.

[jieyouxu]

Thanks, a few issues

[jieyouxu]

Problem: test name is wrong, should be #46471

[rust-log-analyzer]

The job tidy failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[TIMING] core::build_steps::tool::Tidy { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu } -- 0.000
fmt check
fmt: checked 6279 files
tidy check
tidy error: Stray file with UI testing output: "/checkout/tests/ui/trait-bounds/incorrect-self-type-in-trait-impl-48276.stderr"
Checking tidy rustdoc_json...
No error code explanation was removed!
tidy: Skipping binary file check, read-only filesystem
removing old virtual environment
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'venv'
---

added 291 packages in 37s
Running eslint on rustdoc JS files
info: ES-Check: there were no ES version matching errors!  🎉
some tidy checks failed
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:01:58
  local time: Wed Jul 30 04:43:15 UTC 2025
  network time: Wed, 30 Jul 2025 04:43:15 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

[jieyouxu]

tidy error: Stray file with UI testing output: "/checkout/tests/ui/trait-bounds/incorrect-self-type-in-trait-impl-48276.stderr"

[jieyouxu]

Thanks, can you squash after removing stray stderr?

[petrochenkov]

@Oneirical
Do you use https://github.com/petrochenkov/classifui for doing this work?
The tool was discussed a lot in the previous issue (#73494), but #133895 removed any mentions of it for some reason.
It really helps to 1) select the test that can be moved with high confidence and 2) keep contents of the subdirectories self-consistent.