fix: Reject async assoc fns of #[const_trait] in ast_passes

[ShoyuVanilla]

Fixes #117629

[rustbot]

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[rust-log-analyzer]

The job aarch64-gnu-llvm-19-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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test [crashes] tests/crashes/116947.rs ... ok
test [crashes] tests/crashes/117392.rs ... ok
test [crashes] tests/crashes/117392-2.rs ... ok
test [crashes] tests/crashes/117460.rs ... ok
2025-08-04T15:39:51.122894Z ERROR compiletest::runtest: fatal error, panic: "crashtest no longer crashes/triggers ICE, hooray! Please give it a meaningful name, add a doc-comment to the start of the test explaining why it exists and move it to tests/ui or wherever you see fit. Adding 'Fixes #<issueNr>' to your PR description ensures that the corresponding ticket is auto-closed upon merge. If you want to see verbose output, set `COMPILETEST_VERBOSE_CRASHES=1`."
test [crashes] tests/crashes/117629.rs ... FAILED
test [crashes] tests/crashes/117496.rs ... ok
test [crashes] tests/crashes/117795.rs ... ok
test [crashes] tests/crashes/117808.rs ... ok
test [crashes] tests/crashes/118038.rs ... ok
---
failures:

---- [crashes] tests/crashes/117629.rs stdout ----

error: crashtest no longer crashes/triggers ICE, hooray! Please give it a meaningful name, add a doc-comment to the start of the test explaining why it exists and move it to tests/ui or wherever you see fit. Adding 'Fixes #<issueNr>' to your PR description ensures that the corresponding ticket is auto-closed upon merge. If you want to see verbose output, set `COMPILETEST_VERBOSE_CRASHES=1`.

thread '[crashes] tests/crashes/117629.rs' panicked at src/tools/compiletest/src/runtest/crashes.rs:17:18:
fatal error
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace