Move run-pass tests to ui

This is the second attempt at doing #53994 (which was previously reverted in #54530).

The issue with inability to run the test suite in a faster way (#54047) that motivated the revert was recently addressed by #61755.

r? @Centril

…acrum

Remove vestigial CI job msvc-aux.

This CI job isn't really doing anything, so it seems prudent to remove it.

For some history:
* This was introduced in rust-lang#48809 when the msvc job was split in two to keep it under 2 hours (oh the good old days). At the time, this check-aux job did a bunch of things:
    * tidy
    * src/test/pretty
    * src/test/run-pass/pretty
    * src/test/run-fail/pretty
    * src/test/run-pass-valgrind/pretty
    * src/test/run-pass-fulldeps/pretty
    * src/test/run-fail-fulldeps/pretty
* Tidy was removed in rust-lang#60777.
* run-pass and run-pass-fulldeps moved to UI in rust-lang#63029
* src/test/pretty removed in rust-lang#58140
* src/test/run-fail moved to UI in rust-lang#71185
* run-fail-fulldeps removed in rust-lang#51285

Over time through attrition, the job was left with one lonely thing: `src/test/run-pass-valgrind/pretty`. And of course, this wasn't actually running the "pretty" tests. The normal `run-pass-valgrind` tests ran, and then when it tried to run in "pretty" mode, all the tests were ignored because compiletest thought nothing had changed (apparently compiletest isn't fingerprinting the mode?  Needs more investigation…). `run-pass-valgrind` is already being run as part of `x86_64-msvc-1`, so there's no need to run it here.

I've taken the liberty of removing `src/test/run-pass-valgrind/pretty` as a distinct test. I'm guessing from the other PR's that the pretty tests should now live in `src/test/pretty`, and that the team has moved away from doing pretty tests on other parts of the `src/test` tree.

…acrum

Remove vestigial CI job msvc-aux.

This CI job isn't really doing anything, so it seems prudent to remove it.

For some history:
* This was introduced in rust-lang#48809 when the msvc job was split in two to keep it under 2 hours (oh the good old days). At the time, this check-aux job did a bunch of things:
    * tidy
    * src/test/pretty
    * src/test/run-pass/pretty
    * src/test/run-fail/pretty
    * src/test/run-pass-valgrind/pretty
    * src/test/run-pass-fulldeps/pretty
    * src/test/run-fail-fulldeps/pretty
* Tidy was removed in rust-lang#60777.
* run-pass and run-pass-fulldeps moved to UI in rust-lang#63029
* src/test/pretty removed in rust-lang#58140
* src/test/run-fail moved to UI in rust-lang#71185
* run-fail-fulldeps removed in rust-lang#51285

Over time through attrition, the job was left with one lonely thing: `src/test/run-pass-valgrind/pretty`. And of course, this wasn't actually running the "pretty" tests. The normal `run-pass-valgrind` tests ran, and then when it tried to run in "pretty" mode, all the tests were ignored because compiletest thought nothing had changed (apparently compiletest isn't fingerprinting the mode?  Needs more investigation…). `run-pass-valgrind` is already being run as part of `x86_64-msvc-1`, so there's no need to run it here.

I've taken the liberty of removing `src/test/run-pass-valgrind/pretty` as a distinct test. I'm guessing from the other PR's that the pretty tests should now live in `src/test/pretty`, and that the team has moved away from doing pretty tests on other parts of the `src/test` tree.