test_server_setup: allocate two server-data blobs, for watches and timeouts

test_server_setup: allocate two server-data blobs, for watches and timeouts

This is similar to how ConnectionData works. Without this change, we
deserve to segfault: when the first set of callbacks (either watches or
timeouts) is cleaned up, we unref the server and loop, and free sd;
when the second set of callbacks is cleaned up, we use-after-free sd,
the server and the loop, then double-free sd.

However, due to fd.o #33277 we don't even get that far, because we've
already died with an assertion failure.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=33277