Remove the temp files if something goes wrong.

cc #33417

For legacy reasons (presumably), Windows does not permit files name aux.

Instead of finding aux-build files in `auxiliary`, we now search for an
`aux` directory relative to the test. So if your test is
`compile-fail/foo.rs`, we would look in `compile-fail/aux`.  Similarly,
we ignore the `aux` directory when searching for tets.

Also, promote the for loop iterating over revisions out into the
top-level method, whereas before it was pushed down instead each test's
method. Not entirely clear that this was the right call.

Cleanup of E0389

Added type-d out version of type in E0389 description

This should be `have` instead of `has`.

Since these impls can be scattered around quite a bit, it is nice
to be able to jump to the location where individual methods and
trait impls are defined.

Fixes: #30416

Both debuggers are viable in some capacity on all tier-1 platforms,
and people often ask for rust-lldb on Linux or rust-gdb on OS X.

This is safe since the borrow checker ensures that we have the only
mutable reference to the struct, thus we can safely borrow its interior.

Tracking issue is #33444.

The definition of this value recently changed slightly. It no
longer corresponds directly to the target triple.

Also shuffled things around to make the order of cfg descriptions more
logical and added text related them to the target triple.

cc #33403