Retire a misleading construct

The port may not be hardcoded, it is still available for other processes
to steal during the race between `varnish v1 -stop` and the next `varnishd`
execution.

bin/varnishtest/tests/c00003.vtc

 varnishtest "Check that we fail to start with erroneous -a/-b arguments"
 
-varnish v1 -vcl {
-	backend dummy { .host = "${bad_backend}"; }
-} -start -stop
-
 # Duplicate -a arguments
+# XXX: this cannot be tested reliably, we tolerate port collision
 shell -err -match "have same address|already in use" {
-	varnishd -d -a 127.0.0.1:${v1_port} -a 127.0.0.1:${v1_port} \
-	    -b localhost:80
+	varnishd -d -a 127.0.0.1:38484 -a 127.0.0.1:38484 -b localhost:80
 }
 
 # -a bad protocol specs