test_emdawnwebgpu_link_test is flaky

This error showed up on the emscripten-releases bots recently:

```
system_libs:INFO: compiled 1 inputs in 0.54s
cache:INFO: - ok
cache:INFO: deleting cached file: /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a
ports:INFO: retrieving port: mpg123 from https://www.mpg123.de/download/mpg123-1.26.2.tar.bz2
test_embind_tsgen_val (test_other.other) ... ok (7.87s)
wasm-ld: error: cannot open /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a: No such file or directory
em++: error: '/Volumes/Work/s/w/ir/x/w/install/bin/wasm-ld -o a.out.wasm /Volumes/Work/s/w/ir/x/t/emtest_tmwyofnz/emscripten_temp_ushsxhk4/test_emdawnwebgpu_link_test_0.o -L/Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten -L/Volumes/Work/s/w/ir/x/w/install/emscripten/src/lib /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a -lGL-getprocaddr -lal -lhtml5 -lstubs-debug -lnoexit -lc-debug -ldlmalloc-debug -lcompiler_rt -lc++-debug-noexcept -lc++abi-debug-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr /Volumes/Work/s/w/ir/x/t/emtest_tmwyofnz/tmpwk4_fj7klibemscripten_js_symbols.so --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_get_current --export=emscripten_stack_init --export=_emscripten_stack_alloc --export=__wasm_call_ctors --export=_emscripten_stack_restore --export=malloc --export=free --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export-if-defined=main --export-if-defined=__main_argc_argv --export-if-defined=fflush --export-table -z stack-size=65536 --no-growable-memory --initial-heap=16777216 --no-entry --stack-first --table-base=1' failed (returned 1)
None
None
test_emdawnwebgpu_link_test_closure_assertions (test_other.other) ... FAIL
```

It looks like maybe one is deleting a file that another test is going to use. See `deleting cached file: /Volumes/Work/s/w/ir/x/w/install/emscripten/cache/sysroot/lib/wasm32-emscripten/libemdawnwebgpu-00c5e8e9-O0.a`