tests: bump server-side delay in timeout test
tests: bump server-side delay in timeout test

To add a bit of safety margin in case the system running the test-suite
is under heavy load, which may result in the main thread completing a
slightly larger chunk of the sleep before the worker thread gets around
to attempting I/O. This means the worker may end up succeeding instead
of timing out.

GNOME/glib-networking,GNOME/glib-networking,GNOME/glib-networking