Tidy up `dump-ice-to-disk` and make assertion failures dump ICE messages

A bit of clean up to the `dump-ice-to-disk` test.

- Fixes/updates the top-level comment.
- Add a FIXME pointing to rust-lang#128911 for flakiness.
- Instead of trying to manually cleanup `rustc-ice*.txt` dumps, run each test instance in a separate temp directory.
- Explicitly make `RUSTC_ICE` unavailable in one of the `-Zmetrics-dir` test case to not have interference from environment.
- Make assertion failures (on ICE dump line count mismatch) extremely verbose to help debug why this test is flakey in CI (rust-lang#128911).

Contains a fix by `@saethlin` in rust-lang#128909, should wait until that is merged then rebase on top.

try-job: aarch64-gnu
try-job: aarch64-apple
try-job: x86_64-msvc
try-job: i686-mingw
try-job: test-various

…llaumeGomez

Rollup of 8 pull requests

Successful merges:

 - rust-lang#128273 (Improve `Ord` violation help)
 - rust-lang#128807 (run-make: explaing why fmt-write-bloat is ignore-windows)
 - rust-lang#128903 (rustdoc-json-types `Discriminant`: fix typo)
 - rust-lang#128905 (gitignore: Add Zed and Helix editors)
 - rust-lang#128908 (diagnostics: do not warn when a lifetime bound infers itself)
 - rust-lang#128909 (Fix dump-ice-to-disk for RUSTC_ICE=0 users)
 - rust-lang#128910 (Differentiate between methods and associated functions in diagnostics)
 - rust-lang#128923 ([rustdoc] Stop showing impl items for negative impls)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup merge of rust-lang#128909 - saethlin:run-make-ice-yes, r=jieyouxu

Fix dump-ice-to-disk for RUSTC_ICE=0 users

Before this change, the test fails if you run it with `RUSTC_ICE=0`.

…iler-errors

Tidy up `dump-ice-to-disk` and make assertion failures dump ICE messages

For the future traveler: **if you did a `git blame` and found this PR that last modified `dump-ice-to-disk` because the test failed in a completely unrelated PR, then I'm afraid our ICE dump may have regressed or somehow behaves differently on `i686-mingw`.**

A bit of clean up to the `dump-ice-to-disk` test.

- Fixes/updates the top-level comment.
- Add a FIXME pointing to rust-lang#128911 for flakiness.
- Instead of trying to manually cleanup `rustc-ice*.txt` dumps, run each test instance in a separate temp directory.
- Explicitly make `RUSTC_ICE` unavailable in one of the `-Zmetrics-dir` test case to not have interference from environment.
- Make assertion failures (on ICE dump line count mismatch) extremely verbose to help debug why this test is flakey in CI (rust-lang#128911).

Contains a fix by `@saethlin` in rust-lang#128909, should wait until that is merged then rebase on top.

try-job: aarch64-gnu
try-job: aarch64-apple
try-job: x86_64-msvc
try-job: i686-mingw
try-job: test-various

…iler-errors

Tidy up `dump-ice-to-disk` and make assertion failures dump ICE messages

For the future traveler: **if you did a `git blame` and found this PR that last modified `dump-ice-to-disk` because the test failed in a completely unrelated PR, then I'm afraid our ICE dump may have regressed or somehow behaves differently on `i686-mingw`.**

A bit of clean up to the `dump-ice-to-disk` test.

- Fixes/updates the top-level comment.
- Add a FIXME pointing to rust-lang#128911 for flakiness.
- Instead of trying to manually cleanup `rustc-ice*.txt` dumps, run each test instance in a separate temp directory.
- Explicitly make `RUSTC_ICE` unavailable in one of the `-Zmetrics-dir` test case to not have interference from environment.
- Make assertion failures (on ICE dump line count mismatch) extremely verbose to help debug why this test is flakey in CI (rust-lang#128911).

Contains a fix by `@saethlin` in rust-lang#128909, should wait until that is merged then rebase on top.

try-job: aarch64-gnu
try-job: aarch64-apple
try-job: x86_64-msvc
try-job: i686-mingw
try-job: test-various

…er-errors

Tidy up `dump-ice-to-disk` and make assertion failures dump ICE messages

For the future traveler: **if you did a `git blame` and found this PR that last modified `dump-ice-to-disk` because the test failed in a completely unrelated PR, then I'm afraid our ICE dump may have regressed or somehow behaves differently on `i686-mingw`.**

A bit of clean up to the `dump-ice-to-disk` test.

- Fixes/updates the top-level comment.
- Add a FIXME pointing to rust-lang#128911 for flakiness.
- Instead of trying to manually cleanup `rustc-ice*.txt` dumps, run each test instance in a separate temp directory.
- Explicitly make `RUSTC_ICE` unavailable in one of the `-Zmetrics-dir` test case to not have interference from environment.
- Make assertion failures (on ICE dump line count mismatch) extremely verbose to help debug why this test is flakey in CI (rust-lang#128911).

Contains a fix by `@saethlin` in rust-lang#128909, should wait until that is merged then rebase on top.

try-job: aarch64-gnu
try-job: aarch64-apple
try-job: x86_64-msvc
try-job: i686-mingw
try-job: test-various