Setting GLOBAL_ROUTE_ARGS in SWEEP variables gets overriden

[jeffng-or]

In the current SWEEP base configuration, we're setting GLOBAL_ROUTE_ARGS to increase the iterations from 5 to 30, but the GRT run is run with 5 iterations:

Running global_route.tcl, stage 5_1_grt
global_route -congestion_report_file bazel-out/k8-fastbuild/bin/reports/asap7/BoomTile/base/congestion.rpt -congestion_iterations 5 -congestion_report_iter_step 5 -verbose

So, we can't run experiments where we sweep through different iteration values, since it's getting overridden by:

    stage_arguments = {
        "grt": {
            # global route is futile for now, so do a few iterations to
            # get a global route artifact with .odb and .rpt file
            "GLOBAL_ROUTE_ARGS": "-congestion_iterations 5 -congestion_report_iter_step 5 -verbose",
        },
    },

[jeffng-or]

Think #201 will work