flaky standalone tests with BrokenPipe

[andrewrk]

Zig version: 0.12.0-dev.880+1033d7101

It sometimes fails on the CI:

+ stage3-release/bin/zig build test docs --maxrss 21000000000 -fqemu -fwasmtime -Dstatic-llvm -Dtarget=native-native-musl --search-prefix /home/ci/deps/zig+llvm+lld+clang-x86_64-linux-musl-0.12.0-dev.203+d3bc1cfc4 --zig-lib-dir /home/ci/actions-runner2/_work/zig/zig/build-release/../lib
test.standalone.issue_13970.run test: error: unable to spawn /home/ci/actions-runner2/_work/zig/zig/build-release/zig-local-cache/o/fe77cc4d2ac9938588375bdcbc9772c9/test: BrokenPipe
Build Summary: 4861/5014 steps succeeded; 149 skipped; 1 failed; 136347/142599 tests passed; 6252 skipped (disable with --summary none)
test transitive failure
+- test-standalone transitive failure
   +- standalone.issue_13970.test transitive failure
      +- run test failure
error: the following build command failed with exit code 1:
/home/ci/actions-runner2/_work/zig/zig/build-release/zig-local-cache/o/1ee52d9ed3272f5688c6c566f6d78e40/build /home/ci/actions-runner2/_work/zig/zig/build-release/stage3-release/bin/zig /home/ci/actions-runner2/_work/zig/zig /home/ci/actions-runner2/_work/zig/zig/build-release/zig-local-cache /home/ci/actions-runner2/_work/zig/zig/build-release/zig-global-cache test docs --maxrss 21000000000 -fqemu -fwasmtime -Dstatic-llvm -Dtarget=native-native-musl --search-prefix /home/ci/deps/zig+llvm+lld+clang-x86_64-linux-musl-0.12.0-dev.203+d3bc1cfc4 --zig-lib-dir /home/ci/actions-runner2/_work/zig/zig/build-release/../lib

Also, the test has an unhelpful name. Instead of issue_13970, it should be named after the thing it is testing.

[andrewrk]

Another:

test
+- test-standalone
   +- standalone_test_cases
      +- standalone_test_cases.test_runner_path
         +- run test failure
error: unable to spawn /home/ci/actions-runner6/_work/zig/zig/build-release/zig-local-cache/o/84724f1fb8fec8324a85b8a625655cad/test: BrokenPipe