Multiple issues in the runtime system test

There are multiple issues in the runtime system test:

1. timing can fail on heavily loaded machine
2. some tests are no-op because they check for generic named error and when the named has wrong configuration it always fails
3. on macOS, the PATH_MAX is only 1024 so the test that uses overly long configuration file name would always fail
4. various little nits and bits (shellcheck cleanness, missing set -e)

This issue is offspring of !2572 (closed) MR.