fix: setup invalid header for kestrel & http.sys

[DeagleGross]

changed to the same client and same request sending to both kestrel & http.sys and both are responding in same manner. shows kestrel being a bit slower than http.sys (85k RPS vs 90k RPS) on perf lab machines.

Socket errors are reporting 2x for Kestrel due to client specifics. we dont care really: the only interesting value is RPS & that all requests are not successful

kestrel:

| Max Global CPU Usage (%)  | 81                  |
| Max Process CPU Usage (%) | 80                 |
| Max Global CPU Usage (%)  | 89                  |
| Connections               | 32                  |
| Bad responses             | 83,051              |
| Requests                  | 236,919             |
| Requests/sec              | 5,535               |
| Socket Errors             | 153,868             |

http.sys:

| Max Global CPU Usage (%)  | 84                 |
| Max Process CPU Usage (%) | 1                 |
| Connections               | 32                  |
| Bad responses             | 90,879              |
| Requests                  | 181,762             |
| Requests/sec              | 6,055               |
| Socket Errors             | 90,883              |