Remove an OBE as can be test case from 2011

This is from before the introduction of workspace overflow detection.
Since then we would never silently process failing string assembly.

bin/varnishtest/tests.disabled/r00693.vtc

-varnishtest "check boundary condition on vrt_assemble_string()"
-
-feature 64bit
-
-server s1 {
-	rxreq
-	expect req.http.baz == <undef>
-	txresp -status 201
-
-	rxreq
-	expect req.http.baz == <undef>
-	txresp -status 202
-
-	rxreq
-	expect req.http.baz == "BAZ"
-	txresp -status 203
-
-} -start
-
-varnish v1 -arg "-p workspace_client=3072" -vcl+backend {
-
-	sub vcl_recv {
-		set req.http.foo =
-			req.http.bar +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcdef" + "0123456789abcdef" +
-			"0123456789abcde";
-		set req.http.baz = "BAZ";
-		return (pass);
-	}
-	sub vcl_hash {
-		hash_data(req.url);
-		return (lookup);
-	}
-} -start
-
-client c1 {
-	# This should soak up all bytes but the last in the workspace
-	txreq -hdr "foo: x" -hdr "bar: A"
-	rxresp
-	expect resp.status == 201
-
-	# This should soak up all bytes in the workspace
-	txreq -hdr "foo: x" -hdr "bar: AB"
-	rxresp
-	expect resp.status == 202
-
-	# This overcommits the workspace, failing the "bar" set,
-	# Thus allowing the "baz" set to work.
-	txreq -hdr "foo: x" -hdr "bar: ABC"
-	rxresp
-	expect resp.status == 203
-
-} -run