Perform deeper compiletest path normalization for `$TEST_BUILD_DIR` to account for compare-mode/debugger cases, and normalize long type file filename hashes
Fixes#136510.
### Summary
- Whereas previously `$TEST_BUILD_DIR` is a normalization of `/path/to/build/test/<test_suite_name>/`, we now more deeply normalize. `$TEST_BUILD_DIR` now becomes a normalization of `/path/to/build/test/<test_suite_name>/<subdirs>/$name.$revision.$compare_mode.$debugger/` to normalize away path name differences when `--compare-mode` and/or `--debugger` are specified.
- We also centralize the normalization of long type name hashes
cf. https://github.com/rust-lang/rust/pull/136328#discussion_r1936760908.
### Review advice
- Best reviewed commit-by-commit.
- Split into 3 commits:
- **Commit 1**: compiletest changes to have `$TEST_BUILD_DIR` more deeply normalize.
- **Commit 2**: remove per-test hacks for long type path hash normalizations, and rebless tests *specifically* affected by that.
- **Commit 3**: rebless other tests that were changed as a side-effect of deeper `$TEST_BUILD_DIR` normalizations.
**Commit 2** is created via first finding tests that try to perform long type file hash normalizations on an ad hoc, per-test basis:
```
rg --no-ignore -l --no-ignore -F -e "long-type" tests/ui/**/*.rs
```
<details>
<summary>Tests with ad hoc long-type hash normalizations</summary>
```
tests/ui/type_length_limit.rs
tests/ui/traits/on_unimplemented_long_types.rs
tests/ui/regions/issue-102374.rs
tests/ui/recursion/recursion.rs
tests/ui/recursion/issue-83150.rs
tests/ui/recursion/issue-23122-2.rs
tests/ui/methods/inherent-bound-in-probe.rs
tests/ui/issues/issue-67552.rs
tests/ui/issues/issue-37311-type-length-limit/issue-37311.rs
tests/ui/issues/issue-20413.rs
tests/ui/issues/issue-8727.rs
tests/ui/infinite/infinite-instantiation.rs
tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.rs
tests/ui/higher-ranked/trait-bounds/hrtb-doesnt-borrow-self-1.rs
tests/ui/higher-ranked/trait-bounds/hrtb-doesnt-borrow-self-2.rs
tests/ui/higher-ranked/trait-bounds/hang-on-deeply-nested-dyn.rs
tests/ui/error-codes/E0275.rs
tests/ui/diagnostic-width/secondary-label-with-long-type.rs
tests/ui/diagnostic-width/long-e0277.rs
tests/ui/diagnostic-width/non-copy-type-moved.rs
tests/ui/diagnostic-width/long-E0308.rs
tests/ui/diagnostic-width/E0271.rs
tests/ui/diagnostic-width/binop.rs
```
</details>
These ad hoc normalizations were removed, and they are reblessed.
r? `````@lqd`````
9aaf46ea23