Tests fail with LLVM 19 due to unexpected "'+avx512er' is not a recognized feature for this target (ignoring feature)" output

[zmodem]

For example, from https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/28362

thread 'main' panicked at /var/lib/buildkite-agent/builds/rust-llvm-integrate/llvm-project/rust-llvm-integrate-prototype/tests/run-make/non-unicode-env/rmake.rs:11:5:
assertion `left == right` failed
  left: "'+avx512er' is not a recognized feature for this target (ignoring feature)\n'+avx512er' is not a recognized feature for this target (ignoring feature)\n'+avx512pf' is not a recognized feature for this target (ignoring feature)\n'+avx512pf' is not a recognized feature for this target (ignoring feature)\n'+avx512er' is not a recognized feature for this target (ignoring feature)\n'+avx512er' is not a recognized feature for this target (ignoring feature)\n'+avx512pf' is not a recognized feature for this target (ignoring feature)\n'+avx512pf' is not a recognized feature for this target (ignoring feature)\nerror: environment variable `NON_UNICODE_VAR` is not a valid Unicode string\n --> non_unicode_env.rs:2:13\n  |\n2 |     let _ = env!(\"NON_UNICODE_VAR\");\n  |             ^^^^^^^^^^^^^^^^^^^^^^^\n  |\n  = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)\n\nerror: aborting due to 1 previous error\n\n"
 right: "error: environment variable `NON_UNICODE_VAR` is not a valid Unicode string\n --> non_unicode_env.rs:2:13\n  |\n2 |     let _ = env!(\"NON_UNICODE_VAR\");\n  |             ^^^^^^^^^^^^^^^^^^^^^^^\n  |\n  = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)\n\nerror: aborting due to 1 previous error\n\n"
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
------------------------------------------

(And many more.)

I think this is due to llvm/llvm-project@4def1ce

Should we just drop these from compiler/rustc_target/src/target_features.rs ?

[zmodem]

cc @durin42 @krasimirgg