Add benchmarks to CI testing, when ENABLE_BENCHMARKS=ON

Although we are building ``gbenchmark`` and the ``blt_benchmark_smoke`` test when blt is configured with ``ENABLE_BENCHMARKS=ON``, we are not actually running the benchmark smoke test in our CI builds.

To do so, we need to add
```bash
make run_benchmarks
```
to the CI builds.

Start by locating the CI build configuration and the path that enables ENABLE_BENCHMARKS=ON. Check how the CI build invokes make, then add make run_benchmarks and verify that the blt_benchmark_smoke test runs successfully in CI.

Written by the indexing model from the issue text.