flake: `TestServingBin`

[dannykopping]

https://github.com/coder/coder/actions/runs/14446231243/job/40507406796?pr=17363

=== FAIL: site TestServingBin/Extract_and_serve_bin/bin/coder-linux-amd64#01 (0.00s)
    site_test.go:507: 
        	Error Trace:	/home/runner/work/coder/coder/site/site_test.go:507
        	Error:      	Received unexpected error:
        	            	Get "http://127.0.0.1:36677/bin/coder-linux-amd64": net/http: HTTP/1.x transport connection broken: http: CloseIdleConnections called
        	Test:       	TestServingBin/Extract_and_serve_bin/bin/coder-linux-amd64#01
        	Messages:   	http do failed